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Ilfeld Harz Mountains: Thuringia, Germany.

The world's finest crystal specimens of manganite came from small manganese workings near the town of Ilfeld (the type locality) at intervals between ca. 1700 and the final closure of the mines in 1922. The brilliant black manganite crystals are prized by mineral collectors worldwide, and so many were recovered that they still appear regularly on the market. Ilfeld is also the type locality for another manganese oxide: hausmannite.

INTRODUCTION

Mineral collectors everywhere know that the Harz Mountains in north-central Germany are exceptionally rich in metallic ore deposits, especially in the more rugged Upper Harz (Oberharz) in the northwestern sector. Most of the great and famous (and all now extinct) Harz mineral localities--Saint Andreasberg, Bad Grund, Clausthal-Zellerfeld, Altenau; the Rammelsberg mine, where mining for silver began in 968 A.D.--lie in the Upper Harz. However, the tiny manganese-mining district which flourished for two centuries near the town of Ilfeld lies in the Lower Harz (Unterharz), near the midpoint of the Harz massif's southern margin. The last mining activity near Ilfeld ceased in 1922, but the simple statement of Peter Bancroft (1984) that "Manganite is synonymous with Ilfeld" remains true today: this is without doubt the world's best locality for crystal specimens of the black manganese hydroxide. Rarely, the district has also provided good specimens of hausmannite, pyrolusite, pseudomorphs of hausmannite after manganite, and pseudomorphs of pyrolusite after calcite--but it is almost entirely to its wonderful manganite specimens that Ilfeld owes its fame in the world of mineral collecting.

The Harz Mountains consist of a geologically complex, oval-shaped massif measuring 110 km from northwest to southeast and a maximum of 35 km from north to south. Uplifted by block faulting during the Late Cretaceous, these self-contained "mountains" are actually a region of irregular rolling hills and terraced plateaus, with dense forests of spruce higher up and of beech and oak lower down. There are steep, rough stream drainages (with the occasional waterfall), and small caves in formations of limestone, dolomite and gypsum; wild canaries once lived in hillside fastnesses.

In German folk culture and in the high culture of the Romantic movement, the Harz were regarded as a sort of citadel of wild Nature: among romantic-age figures who sojourned there were the poets Heine and Schiller, the taleteller Hans Christian Andersen, and the great poet and amateur scientist Johann Wolfgang von Goethe (1749-1832). During the early 19th century Goethe, especially, came often to the Harz to pursue geological studies (and, probably, to pursue mineral specimens for his collection). Two scenes in his epic poem/drama Faust dramatize a legend of medieval Walpurgisnacht ("witches' night") celebrations held on May Eve (April 30/May 1) on the Brocken, the highest peak of the Harz--with satanic powers ranging over the hilltops and in the dark glens.

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Real 20th-century history offered up its own demons: Heinrich Himmler and other Nazi leaders toyed with the idea of setting up a Festung (fortress) in the Harz which would turn back the invading Allies. No such last stand ever occurred, although, for a few days after V-E Day, remnants of Waffen SS and Volkssturm units in the Harz did indeed play come-and-get-us with elements of the U.S. Fifth Armored Division (see en.wikipedia.org/wiki/Harz; Martin, 1950).

The Cold War boundary between the two Germanies sundered the western third of the Harz from the eastern two-thirds for more than four decades, but now, with artificial dividing lines down and all demons cast out, the beautiful hills attract tourists, vacationers, hikers and bikers, most of them Germans from other parts of the country, who seek a break from urbanized life or even, in Goethe's tradition, a sort of dreamy corrective to it. Some visitors--also following Goethe--are mineral collectors, and look for old ore dumps to dig on or mining museums to visit, or local collectors who might have surprises on view in parlor showcases.

LOCATION

The town of Ilfeld--present population about 3,000--straddles the valley of the little Behre River at a site 9 km north of Nordhausen and 3 km east of Appenrode. Politically, the town and nearby mines lie in the northernmost part of the German state of Thuringen (Thuringia), 10 km east of the old Cold War boundary and 20 km east of the famous Saint Andreasberg mining district. Recorded history for Ilfeld begins around the year 1100, when Count Elger I built a castle, the Ilburg, on a height overlooking the present site of the town. In 1154 the term "Ilevelt" first appeared in a document issued by the Saxon duke Henry the Lion, then passing through on a pilgrimage to the Holy Land. In 1189 Count Elger II and his wife Lutrude founded a monastery around which, in the mid-14th century, the village of Ilfeld began to grow. Chiefly known today (outside mineralogical circles) as a spa town and health resort, Ilfeld has remained through the centuries a quiet, bucolic place. Perhaps its busiest contemporary activities are the gatherings of hikers' and bikers' excursion tours bound for the forested hills, mainly those to the northwest of town, where manganese ore was once mined.

Excursionists often gather at an old half-timbered building called the Braunsteinhaus, about 2 km northwest of the center of Ilfeld. Named for braunstein, the old term for manganese oxide ore, the original Braunsteinhaus building served as a nexus of mining activity ever since it was first built during the 1750s near the mines on Monchenberg ("Monk's Hill"). A few years later it was relocated 400 meters or so to the northeast, where mining was more active in the area soon to be called Braunsteinzeche. At various times in the late 18th century and throughout the 19th, when mining flourished, the house was expanded in stages, and satellite buildings, including a colliery, stamp mill, and storage sheds for mining equipment, were added, while the original building provided a headquarters for mine administration. In 1979 the former Zechenhaus ("colliery") at the Baunsteinhaus complex began its present career as a Gaststatte (restaurant/inn). Old, heavily overgrown dumps and the remains of prospect pits on the slopes of Harzeburg are easily reached on foot from this old dowager of a structure.

The belt of manganese ore veins begins in the Silberbachtal ("silver creek valley"), about 2.5 km northwest of the town of Ilfeld, and strikes generally west-northwest until ending at the Holzapfelkopf ("Crabapple Peak"), 1 km northeast of the town of Sulzhayn--a total length of about 5 kilometers. The ore veins and stringers were all quite small and nearly horizontal or roughly parallel with the surface, extending laterally for only about 10 to 15 meters, exceptionally 60 meters, and averaging 45 to 60 centimeters thick. Without exception the richest parts of the veins were less than 10 meters below the surface, pinching out or becoming barren of ore further down; such veins were colloquially called Rasenlaufern ("sod runners"). All ore and specimens came from individual tiny prospects and shallow underground workings, few of which were ever given individual names. Since there was no single dominant mine, nearly all specimen labels say simply "Ilfeld," or occasionally "Sulzhayn" or "Appenrode."

The easternmost part of the mining area lay in the Silberbachtal, below the eastern slope of the hill called Harzeburg. During the 19th-century heyday of mining the so-called "Ilfeld-Mangan" mine area in Silberbachtal (one of the few workings to have received its own name) measured 2.1 million square meters, and produced chiefly pyrolusite and hausmannite ore from irregular stringers and pods (Rumscheidt, 1926). The ore zone was about 12 meters deep, striking 80[degrees] northwest and dipping between 76[degrees] and 80[degrees] to the southwest. It extended from the stream valley to the northeastern margin of the Harzeburg, where it ran around the hill's northern edge, finally joining the Oberen Zug ("upper course") of iron and manganese ore veins about 100 meters east of the Braunsteinhaus. There are traces of mining in the Silberbachtal before 1725, the earliest date of reliable written records for the region as a whole.

The Oberen Zug along the northern slopes of the Harzeburg included both iron and manganese ore veins, the latter concentrated immediately south of and upslope from the Braunsteinhaus. In this region of workings, generally called the Braunsteinzeche ("braunstein mining area"), manganite was the chief ore species. Like the Silberbachtal, it was characterized by irregular pods and stringers of ore; consequently, ore exploitation took place in quarry-like open pits and through very short, shallow adits driven into the slope of the Harzeburg from ground near a stream called the Salzwerferbach, almost at the southern portal of the Brainsteinhaus. The Braunsteinzeche area was, with Monchenberg, one of the two sub-districts which produced the very finest known specimens of crystallized manganite (Rumscheidt, 1926).

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However, the region's best, most economically valuable manganese ore was found on the Lower Harzeburg, along the Unterer Zug and Mittlerer Zug ("lower course" and "middle course") of veins running along the southwestern slopes of Harzeburg until ending at a westernmost point at the Salzwerferbach, where the vein system meets the deposits of the Braunsteinzeche. Today the Lower Harzeburg area harbors many remains of open pits and extensive (though overgrown) ore dumps, and is a main destination for hikers along the Bergbauhistorischer Lehrpfad ("Mining-Historical Teaching Trail").

On the other side of the Salzwerferbach and about 300 meters southwest of the Braunsteinhaus lies the hill called Monchenberg (or Kleine Monchenberg), where manganese and iron mining also began very early, i.e. before 1725 (Gaevert, 1981), and where manganite specimens equaling those of Braunsteinzeche were found occasionally (Rumscheidt, 1926). The remains of mining on Monchenberg are clearly visible today, most of them dating from the late, brief period of work during World War I (Liessmann, 1997). The ore-bearing porphyry in this sub-district is brecciated and shot through with stringer veins and isolated pods (called Trumern) of manganese oxides, including good pyrolusite ore; the greatest ore concentrations reached 12 meters thick. During the 19th century an open pit was dug from the top of the hill to a depth of 63 meters, and ore was produced from veinlets and "nests" encountered in the quarry-like excavation (Luedecke, 1896; Bruhns, 1906; Rumscheidt, 1926).

Manganese mining at other sites in the district was less well developed and less economically important. A zone of stringer veins was exploited on the hill called Muhlberg, about 800 meters northwest of the excavations on Monchenberg, and more stringer veins were worked on Hegersberg, about 1 km due north of Monchenberg and 700 meters north-northwest of the Braunsteinhaus. At a point on Hegersburg where two thick veins converged there was a concentration of excellent pyrolusite ore (Rumscheidt, 1926). Very small-scale, intermittent mining also took place on Heiligenberg ("Holy Hill") and Liesenberg ("Gleaning Hill"), further to the northwest.

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The mining district terminated about 1 km northeast of Sulzhayn, on Holzapfelkopf. On this prominence a mine called the Bergmann-shoffnung ("Miners' Hope"), begun in 1838, covered a surface area of 2 million square meters; it was a complex of branching open-pit excavations exploiting a system of ore veins which must have been (for the district) fairly extensive. In the 1920s, just after all mining had ceased, an exposed vein of high-grade manganese ore about 35 cm thick was still visible on Holzapfelkopf (Rumscheidt, 1926).

HISTORY

Iron Mining at Ilfeld

There were once at Ilfeld not only manganese mines, but also mines which exploited iron ore--massive red hematite occurring in veins running roughly parallel to the manganese veins and lying very near them. Hematite veins, for example, on the northern slope of Harzeburg, between the Silberbachtal and Braunsteinzeche manganese-mining areas, form the eastern part of the Oberer Zug system on Harzeburg (shown on the map in Fig. 11). These and other miniscule iron deposits were worked long before any manganese mining began. A letter of 1535 mentions iron mines called "God's Grace" and "Holy Trinity" located on Harzeburg, as well as other iron mines on Monchenberg and at unspecified sites along the stream called the Sachswerferbach (www.manganit.de, 2010). According to Rumscheidt (1926), there was an iron-smelting facility in Ilfeld during some part of the 18th century, and organized exploitation of hematite ores in the Ilfeld district fed its operation. The same source goes on to say that iron mining at Ilfeld ended for good in the very early 19th century, when manganese mining took its place; Bruhns, however, wrote in 1906 that "red iron oxide ores are mined," together with manganese ores, on Monchenberg. However unclear their history, it is quite clear that the iron ore occurrences of the Ilfeld district were small even compared to the manganese ore deposits there--and the literature contains no hint of any significant crystallized minerals having ever emerged from them. Accordingly, the historical survey below restricts its attention to the manganese ore veins of the Ilfeld district.

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The late Middle Ages through the 18th century

Like many centuries-old mining districts, Ilfeld has a history that is preceded by cloudy legends and rumors out of "prehistory"--meaning, in this case, the late Middle Ages, when pulverized manganese oxide ores were employed in the manufacture of high-quality glass for making decorative objects and works of art. Exactly how braunstein was used to make glass was a trade secret closely kept by the glassmakers of Venice, already in the late Middle Ages a renowned glassmaking center. Braunstein being hard to procure in Italy, Venetian glassmakers (the legend goes) sent prospecting teams out into remote territories in search of it, perhaps beginning in the last third of the 15th century. To keep the purpose of their journeys secret (the legend continues), these explorers elaborated a system of myths and codes, and to keep up communication they scratched out secret signs on rock walls. They wore unusual "weather" capes and pointed hats, the hats reminiscent of cowls worn by members of some monastic orders. And such Venetians may or may not have come to the wild northern forests near Ilfeld, and they may or may not have discovered the manganese ore on Monchenberg, which may or may not have been named for these travelers whom some observers called "monks" because of their hats and esoteric behaviors (Liessmann, 1997; www.manganit.de, 2010).

The earliest known written reference to mining around Ilfeld dates to 1535, when unknown parties filed mining claims on Harzeburg. The old records make no reference to manganese ore or any other specific resource. Siemroth (1990) speculates that the manganese oxides may have been mistaken for silver ores, and the claims may have been filed by someone passing through from the silver-rich Erzgebirge or Mansfeld mining regions, or from Saint Andreasberg.

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In his De Re Metallica (1546), the great Renaissance pioneer of mineralogy Georgius Agricola (1494-1555) noted that "stibnite" occurs near Ilfeld. More than two centuries later, in 1754, a Saxon mining official named Henkel observed sarcastically that "the all-around mining expert and country parson" Georgius Agricola must have mistaken black, prismatic crystals of manganese ore for "antimonio," as the antimony sulfide was then often called (Siemroth, 1990). After Agricola, in any case, there are no further mineralogical observations from Ilfeld for 175 years, i.e. until the 1720s.

In 1727 the physician and naturalist Franz Ernst Bruckmann (1697-1753) published his Magnalia Dei in Locis Subterraneis, an ambitious work described by Schuh (2008) as a "guide to mining throughout Europe ... [with] various descriptions of individual mines and entire districts and the materials mined." The work shows that manganese mining at Ilfeld was already under way, a passage in it reading:
  ... on the hill called Monnigskopfe [= Monchenberg?] ... there is
  excellent braunstein ore which looks just like antimonio. The veins
  and stringers of ore are narrow and do not at all reach into the
  depths, but rather lie more or less on the surface. The stone is all
  sent to Holland, and a kentner here at the mines costs half a thaler.
  In 1724, 1,400 kentners were sent to Holland. (Quoted in German
  translations by Rumscheidt, 1926, and Siemroth, 1990)


A kentner--more commonly "zentner"--was a hundredweight: about 50 kg. Siemroth (1990), working with old production documents now in the public records office in Magdeburg, reports that between 1740 and 1785 an average of 200 zentners of Braunstein were exported yearly from Ilfeld to Holland, so, probably, Bruck-mann's "1,400 kentners" is an error for 140 zentners. In Holland, the braunstein was used in the preparation of a dark glaze for bricks and building stones, such as one sees (even today) on old buildings there. A 1797 report on the use of braunstein affirms that "such braunstein goes especially to Holland, where they like to use bricks and tiles which gain firmness and luster from it" (Siemroth, 1990).

In the early 18th century, most of the forested region between Ilfeld and Sulzhayn was the private property of the Count of Stolberg-Wernigerode, and the primitive manganese mines were overseen by this nobleman's Forest Administration. For decades before Bruckmann's 1727 observations, the mines had suffered from haphazard exploitation, despoliation, and general chaotic conditions, and thus in August 1724, at the suggestion of a Forstmeister ("Master of the Forest") named Seibd, Mine Inspector J.G. Sander was appointed to survey the mine workings and to make recommendations for their improvement. His report, issued in January 1725, is full of well-focused, interesting facts, among them that (1) a "main shaft" on Harzeburg had reached a depth of 4 meters; (2) the vein on Heiligenberg was thick, but somewhat impure; (3) the old mines on Monchenberg were closed and flooded, although good outcrops of fragmented braunstein were evident; (4) Silberbach had once yielded good ore but now lay dormant; thick veins were present which would bear further investigation.

Sander suggested that a plan for professional mining be set down, that the scope of mining be expanded, and the price of ore increased. By "professional" mining he chiefly meant a program of stoping to follow the braunstein veins upwards from the valleys--replacing the old, haphazard practice of digging shallow pits and ditches on the tops of hills. He also recommended that existing shafts should be deepened to ascertain whether and how the braunstein continued at depth (Gaevert, 1981).

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The Count's Forest Administration accepted the recommendations and set to work on them at once, albeit not wholly as would be done today: in February 1725 a professional dowser was hired to locate with his divining rod all hitherto unknown braunstein veins. He reported that the richest veins lay on Monchenberg and Heiligenberg, and suggested that mining efforts be focused on these sites and on the established ones on Harzeburg. In March 1725, free prospecting rights for all comers were proclaimed. Increased stoping was instituted, as per Sander's recommendation. By November 1739, Forstmeister Seibd could (and did) report that the mines were in excellent working order, though improving them had cost much money and trouble (Gaevert, 1981).

Throughout the 18th century, most of the orders for braunstein continued to come from Holland. Each year a few hundred zentners of manganese ore were taken in wagons from the Braunsteinhaus to a transshipment point in Wernigerode, and then, via Magdeburg (in care of a merchant named Tilebein), to Hamburg, from whence the barrels of ore were taken by ship to Amsterdam and Rotterdam. The names of some Dutch merchant buyers from the 1770s have been preserved: Boom in Rotterdam; Waeshoff, Heurn and Herchner in Amsterdam. But transporting ore over the Harz made for difficulties in the 18th century. During stops, farmers were paid to guard the ore wagons, but since during spring, summer and fall the farmers were almost exclusively occupied with their fields and properties, it was considered best to ship during winter, notwithstanding that most orders came in at other times of the year. When, in winter, the mountain roads grew perilous, care was taken to locate "good sleighing routes" to Wernigerode.

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The scope and intensity of the mining work was directly dependent on orders for ore. When demand was great, the Forest Administration employed miners for days or weeks at a time, but when orders dwindled, miners were simply laid off indefinitely. Ore production levels, and the number of mines in use, fluctuated wildly. In 1730, in a second part of his Magnalia Dei, Bruckmann reported that nearly all of the workings were dormant (Siemroth, 1990), but in 1740, an Amsterdam merchant named Gerhard having requested that 34 barrels of braunstein be sent to him as soon as possible, expanded crews took large quantities of ore from veins at four mining sites (Gaevert, 1981). In February 1759 only two miners were at work, and in 1766, when complaints from Holland came in to the effect that the braunstein received was "contaminated with earth" and of little value, sales fell off and dubious reserves accumulated.

In 1770 business picked up again thanks to large orders from the Amsterdam traders Waeshoff and Heurn; many miners were quickly hired and were paid by the hour to produce "quantities" of braunstein (Gaevert, 1981; Siemroth, 1990). In Holland--as later in Russia--the manganese oxides were still being used to make glazes for bricks, and for pottery and ceramic wares, and small amounts of manganese still found uses in glassmaking. The alloying of manganese with iron to make steel was fated to wait, of course, until a steel industry began to develop in the mid-19th century.

The 19th century

The 19th century, and in particular the decade of the 1830s, was a "golden age" of manganese mining at Ilfeld. At some time shortly before 1819 there was an administrative change: the Count of Stolberg-Wernigerode transferred authority over the mines from his Forest Service to his Mining Office, headquartered at Buchenberg, near Wernigerode. The Bergschreiber (~ "Secretary of Mining"), a man named Preu, concerned himself closely with the Ilfeld mines, often staying for long periods at the Braunsteinhaus to oversee mining and provide direct guidance to the working miners. His yearly reports, with budget estimates for each coming year, were reviewed by Bergkommissar C. F. Jasche, the representative of the Count's control board. Both of these men devoted themselves chiefly to improving the quality of the braunstein ores (Gaevert, 1981; Liessmann, 1997), for only thus could higher prices be charged and higher profits secured. The direction of the Ilfeld mines was in capable hands.

Support structures around the Braunsteinhaus were greatly improved. In October 1818, Bergschreiber Preu directed that a roomy enclosure be built where valuable ore could be hand-separated from barite, calcite and country rock (earlier this ore-sorting had taken place outdoors); the facility was finished in 1821. In 1819-1820 a stamp mill was added, where barite and clay could be separated from Graubraunstein (gray braunstein, the most impure kind of ore). A dam on Sachswerferbach was constructed, creating a pond from which water could be brought by ditches to the stamp mill--although it was only in rainy periods that the water of the tiny stream sufficed fully for the purpose (Liessmann, 1997). Comfortable living quarters for crew foremen and visiting officials were provided by an expanded Zechenhaus ("colliery house"), the core of the present-day restaurant--although accommodations remained very cramped for common miners who chose to stay overnight at the mines, as many did who sought "overtime" during the busy 1820s and 1830s. Along the routes by which ore was shipped from the Braunsteinhaus to Wernigerode and, by then, other transshipment points in the Harz, checkpoints were set up to monitor the delivery process and improve its efficiency (Gaevert, 2010).

In 1819, 34 men were at work in mines in the Braunsteinzeche, and more were hired in the next few years as operations expanded on Harzeburg, Monchenberg, Heiligenberg and Hegersberg. Mining went on year-round at one or another of several sites, and orders for braunstein from within Germany were increasing, simplifying ore-shipment logistics. New uses for manganese were also being discovered, e.g. in dyes and inks and as an oxidation catalyst in the manufacture of bleaches. The chemical industry found that pyrolusite ([MnO.sub.2], called mangansuperoxide) was especially effective at releasing chlorine from hydrochloric acid (Bruhns, 1906).

In 1835,72 mine workers produced 5,048 zentners of manganese ore (Liessmann, 1997). In 1836, the all-time record year (before the brief period during the First World War, when "modern" technologies were applied), 5,613 zentners of ore were won by a work force of 94 men (Rumscheidt, 1926). This success inspired management to prospect in areas farther to the northwest from the Braunsteinhaus, such as on Liesenburg and Holzapfelkopf. On the latter hill a rich pyrolusite orebody was discovered, and in 1838 the Bergmannshoffnung mine was begun. Another bright spot in the 1830s was the Count's institution of a miners' provident fund to make money available to miners' widows and orphans: a modest "welfare" system which nonetheless added a burden to mining budgets (Gaevert, 1981).

But any ideas of steady, long-term growth were ruled out by the patchy nature of the ore deposits and related economic uncertainties. The veins and stringers of ore kept giving out, and new veins and stringers were not always located quickly. Sales of reserves were spotty; in times of low productivity there was not always enough ore on hand to fill orders. The market price of manganese remained subject to large fluctuations. Short-notice hiring of miners was difficult, as the men in question had all too commonly been laid off in the past and preferred to take more stable jobs.

In the 1830s Russia replaced Holland as the chief foreign customer for braunstein (which the Russians used chiefly in making a chemical bleach for glass manufacture), and the logistics of filling orders became much more challenging than they had previously been. The successes of the mid-1830s very soon gave way to hard times. By 1840 the number of miners at work, 94 in 1836, was down to about 20 (Gaevert, 1981), and in 1849 the production of braunstein was less than 7% of what it had been 13 years earlier (Rumscheidt, 1926). By 1859, only eight men were mining and refining ore at the Braunsteinzeche.

In 1865, Otto von Bismarck was beginning his project of unifying a German Empire under the domination of Prussia, and the powers of local rulers such as the Count of Stolberg-Wernigerode were beginning to erode. On June 24, 1865, a general Prussian mining code was instituted; among its local effects was that the control of the Ilfeld manganese mines now fell to the Hanoverian Mining Office at Clausthal, although the Count's old Mining Office retained supervisory responsibility. In 1869, under the new law according to which all prospecting rights had to be procured from Prussian state agencies, the Count of Stolberg-Wernigerode laid formal claim to two areas, each 22 [km.sup.2], called "Braunsteinzeche" and "Bergmannshoffnung," encompassing all of the known manganese ore occurrences near Ilfeld. The claim was granted, and thus the Count regained the right to work "his" ore deposits. Already by then, though, it was clear that the mining district was in economic decline.

Foreign orders for braunstein came almost to a halt during the Franco-Prussian War of 1870-1871. By 1875, orders were up again, technical improvements at the mine sites were being made, and production rose. In 1876, economic fluctuations brought on a plunge in orders, and work in the mines almost totally ceased. By this time, a major contributing factor to the decline of the mines was the influx of cheap manganese ores from new mines in Spain and India. In early 1877, surprisingly, orders for braunstein from Ilfeld rose sharply again; in 1880, with contributions from some rich veins on Hegersberg, about 1,500 zentners of ore were produced. But production fell off steadily once more after 1882. In 1890 only 98 zentners of ore were produced, and the Count began to entertain the idea of ceasing all mine operations.

An entrepreneur from Nordhausen, Eduard Gossel, offered to lease the mines from the Mine Office and continue mining. The Office was tempted to grant the lease, but since, in the judgment of Bergmeister W. Schleifenbaum, it was highly questionable whether Gossel could mine at a profit, negotiations were broken off. Schleifenbaum pointed out that manganese ores were now being recovered cheaply in Spain and in the Caucasus, while the use of high-quality Ilfeld braunstein in glass manufacture was declining. And, anyway, minable Ilfeld reserves seemed still confined to Rasenlaufer veins just under the surface, most known examples of which were almost completely mined out (Rumscheidt, 1926; Gaevert, 1981).

Early in 1891 the buildings around the Braunsteinhaus, with their entire inventories, were sold off, and the Ilfeld district went dormant until 1916.

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Last Operations: 1916-1922

During World War I, with Germany cut off from global commerce by the British naval blockade, it became vital to exploit domestic resources as fully as possible. Manganese was now needed for alloying steel, and hence was a valuable strategic metal. In 1916 the Sudharzer Schwerspatwerke Max Doring ("Max Doring Southern Harz Barite Company"), the first commercial firm ever to become involved with manganese mining at Ilfeld, leased the old mines from the Count's Mining Office. The company's plan was to reactivate not only the central mines at Braunsteinzeche and on Monchenberg and the southern slopes of Harzeburg, but also the Ilfeld-Mangan mine in Silberbachtal and the Bergmannshoffnung mine on Holzapfelkopf.

During the previous 26 years the mine workings in general, and in particular the shallow underground adits, had deteriorated badly, so an 84-person crew (including women) was set to work in removing debris, repairing the adits, and deepening some of the old shafts. No new ore was produced for several months, but by the end of 1916, 8,000 zentners of manganese oxides had been won--2,400 zentners more than had emerged during the peak year of 1836. The difference was a result of improved technology: the use of mechanical drills attached to air compressors enabled the ore to be extracted far more efficiently than it had been in the 18th and 19th centuries. However, just as in those centuries, the ore was taken in carts to the Zechenhaus and there sorted by hand, processed lightly, and shipped out of the district in wooden barrels (Gaevert, 1981).

In 1917 the Max Doring company was taken over, and the lease to the mines acquired, by the Dresden firm of Pretzschmer und Fritzsching, and intensive mining continued. Large quantities of ore (for Ilfeld) emerged each year up to and including 1921. But after the Versailles Treaty was signed and the blockade lifted in 1919, competition from foreign sources resumed, and, even more discouragingly, the known major zones of ore were almost exhausted and there had been no indications of new ones. On April 1, 1921, all mining around the Braunsteinhaus ceased. On March 31, 1922, the last shift finished work at Ilfeld-Mangan in Silberbachtal, and with this final closure the history of manganese mining at Ilfeld came to an end (Rumscheidt, 1926; Gaevert, 1981).

Although economic circumstances for a renewal of mining briefly looked favorable during the 1930s, no new activities came about in that decade or during the Second World War. For 88 years now the mine sites have known only visitors who dig ferociously in the old dumps for manganite crystals (see later, under "Collecting Manganite"), and docile hikers who follow the Bergbauhistorischer Lehrpfad onto the overgrown slopes of Harzeburg and Monchenberg.

Production

Rumscheidt (1926) offers a total accounting of the production of manganese ore in the Ilfeld district. If one adds together the precisely known production figures for 1819-1890 and 1916-1922 (see Fig. 9), and if for the period 1724-1818 one assumes an average production of 300 zentners per year (a plausible figure, judging from 18th-century documents), one can calculate a total production of about 10,000 tonnes of manganese ore for the whole period 1724-1922. Comparing this with the world's total production of 24 million tonnes of manganese ore in a single year, 1978, reveals the economic insignificance of the Ilfeld occurrence. It is likely that in 1978 (or any later year), the original Ilfeld deposit would never have been mined--unless it were to retrieve showy collector specimens of manganite.

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For that matter, these would have been superb "specimen mines," but for that they were wrongly located in time and place. As fate had it, the mining of this trivially tiny deposit (as one may safely call it) over two centuries made for no special boons to civilization. A few pretty hillsides were violated; a few men found very unsteady employment; manganese oxides went to serve casual decorative ends in some corners of Europe; and financial profits went to enrich the estates of the Counts of Stolberg-Wernigerode. The best, longest-lasting remainders of mining at Ilfeld are the magnificent manganite specimens that may be seen today in museum and private collections worldwide.

GEOLOGY AND MINERALIZATION

The Harz Mountains as a whole are characterized by very complex geology, with diverse rock types forming an intricate patchwork (see map) representing the eroded roots of what were once mountains formed by the Hercynian (also called the Variscan) Orogeny that took place during the Carboniferous period some 350-300 million years ago. During the Cretaceous (140-67 million years ago), block faulting, especially on the northern edge of the Harz, uplifted the mountain roots, forming the present massif, some of which was probably an island in the shallow sea which covered northern Europe in Late Cretaceous times. The Harz are bounded by fairly sharp scarps on their northern and northwestern margins and dip in a gentle, generally uniform way toward their southern margin.

Quite aside from their mineral deposits, the Harz have always been a fertile field for geological study. One area around Goslar is so complex that German geologists call it the "classic [or golden] square mile of geology"--the reference being to a 7.5 km-long "Prussian mile." The term "Hercynian," referring in Europe both to the Carboniferous-age orogeny and to a specific strike direction--northwest-southeast, as for the Harz as a whole--is derived from a Latin version of the word "Harz."

The manganese ore veins of the Ilfeld district are associated exclusively with porphyritic igneous rocks which alternate with sedimentary rocks in the Ilfeld Basin. This basin is a synclinal structure (Luedecke, 1896; Sansoni, 1971) with a long axis running for about 20 km along the southern rim of the Harz, between Bad Sachsa on the west and Neustadt on the east; the town of Ilfeld lies within its eastern third.

The Ilfeld Basin was filled by sediments and eruptive rocks during Lower Permian (called in Germany Rotliegendes) times. The lowermost sedimentary rocks, unconformably overlying Devonian-age shales and graywackes, are conglomerates whose beds reach 50 meters thick (Luedecke, 1896; Sansoni, 1971). Immediately overlying the conglomerates are gray sandstones and clayey shales, the latter shot through with seams of coal (not minable) to 1.6 meters thick. At the top of the sequence come conglomeritic sandstones and red-colored clayey shales, with some irregular, localized limestone units.

All of the sedimentary rocks above the lowest conglomerates are intercalated with flows of extrusive igneous rocks from at least two eruptive episodes, representing the last volcanism in the Harz (Sansoni, 1971). The eruptions produced three basic rock types: tuffs, and two denser, porphyritic types which the German literature calls melanophyres and porphyrites. The tuffs are rich in pumice, some units containing only a bottle-green glass in foamy masses (Hornung, 1894). They are nowhere observed to host manganese ore veins. "Melanophyre" is "a broad term ... for any dark-colored porphyritic igneous rock having a fine-grained groundmass" (Jackson, 1997). The melanophyres of the Ilfeld Basin, which come from the earlier or earliest of the eruptive episodes, are brown to black, with a fine-grained groundmass composed of oligoclase, augite, biotite, apatite and magnetite, with phenocrysts, most of which are tabular crystals of augite (Luedecke, 1896). "Porphyrite" is a term "originally used to distinguish porphyries that contain plagioclase phenocrysts from those that contain alkali feldspar phenocrysts" (Jackson, 1997). The porphyrites of the Ilfeld Basin have plagioclase (oligoclase and andesine), and in some cases spessartine, as phenocrysts in a dark, fine-grained groundmass similar to that of the melanophyres (Luedecke, 1896). Agate nodules that have weathered out from some porphyrites are found at scattered sites between Ilfeld and Bad Sachsa (Siemroth, 1990).

Near-surface, weathered and partially altered porphyrite (sometimes called "bronzite porphyrite") largely determines the morphology of the region and is the exclusive host rock for the manganese ore veins, which have never been observed to penetrate surrounding sedimentary rocks. Both the manganese oxide veins and the nearby hematite veins resulted from low-temperature hydrothermal activity which accompanied tectonic movements during Permian time (Rumscheidt, 1926). Haake et al. (1994) distinguish between late Lower Permian ("Rotliegendes") hydrothermal activity, which formed the hematite veins, and Upper Permian ("Zechstein") activity which formed the manganese oxide veins. The metal-bearing solutions which filled clefts and fissures in the porphyrites, creating the ore veins, percolated also into the most narrow openings, forming impregnation zones characterized not by discrete veins but by dense "nests" of stringers and pods (Trumem), and causing some brecciation of the porphyrite. The trumern zones were commonly mined in open-pit excavations, the largest of which were those on Monchenberg.

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Some of the hydrothermal solutions may have descended into the porphyrites from overlying Zechstein-age rocks (now eroded away), while other solutions may have traveled laterally, bearing metals leached from the porphyrites themselves, while still others may have ascended from plutons, forming hot springs on land surfaces then exposed (Stahl and Ebert, 1952). As noted earlier, the coherent veins of manganese oxides are seldom more than 15 meters long and 60 cm thick. Mining sometimes pursued the trumern zones to depths greater than 60 meters, but more commonly the best ore lay in the coherent veins, much closer to the surface. At depths below about 50 meters, minable veins typically give way to mineralogically and economically uninteresting veins of massive hematite, barite, and quartz.

Gangue species in the manganese veins most commonly included barite, calcite and quartz; rarely, aragonite and siderite occur; extremely rarely (and only in Silberbachtal), rhodochrosite was found. The manganese ore species of the veins are braunite, hausmannite, cryptomelane, "wad" and most commonly, and of greatest economic significance, pyrolusite and manganite. The old miners called the ore veins which carried the beautiful crystals of manganite Schlackengange ("cinder veins"); they called the solidly filled veins of massive ore Schalengange ("shell veins").

MINERALS

Aragonite [CaCO.sub.3]

Aragonite was noted by Zincken (1825) as a rare component of the gangue; the existence of crystals from Ilfeld is doubtful.

Barite [BaSO.sub.4]

Barite is the most common of the gangue species of the manganese veins. It did not form contemporaneously with the manganese oxides but was deposited later, possibly during Late Permian or early Triassic times (Haake et al., 1994). Accordingly the barite and calcite masses are not attached to vein walls but rather form fillings and stringers along the centers of veins (Sansoni, 1971; Siemroth, 1990; Haake et al., 1994). The barite may have come from hydrothermal solutions which had leached barium from small halite deposits elsewhere in the Harz, then descended to the porphyrites through overlying Late Permian (Zechstein) sandstone units (Stahl and Ebert, 1952).

The barite of the ore veins is white, opaque, coarse-grained and very pure (Rumscheidt, 1926). Tantalizingly, the early 19th-century Bergkommissar C. F. Jasche referred in print, without elaboration, to "very large" crystals of barite found in the manganese veins (Jasche, 1838). Siemroth (1990) mentions crystals of barite rarely found overgrown on manganite crystals; Dameron (2008) notes that at Ilfeld barite "occurs (rarely) in white tabular crystals, somewhat thick" with manganite. In short, significant crystallized barite specimens from Ilfeld exist but are extremely rare. The massive, snow-white vein-filling material, when present on specimens, provides a striking contrast to the gleaming black manganite crystals.

Braunite [Mn.sup.2+][Mn.sub.6.sup.3+][SiO.sub.12]

Braunite occurs in good crystals in the manganese deposit at Ohrenstock near Ilmenau, in the Thuringian Forest about 100 km south of Ilfeld, but in the Ilfeld manganese veins it did not form good macrospecimens--lustrous crystals to 5 mm have been noted rarely, and braunite pseudomorphs after manganite occasionally have appeared (www.manganit.de, 2010). Ludecke (1896) and Sansoni (1971) mentioned braunite as an ore species found mixed in small amounts with others at Ilfeld.

Calcite [CaCO.sub.3]

Calcite is, after barite, the second most common gangue species in the manganese veins, and like barite it occurs in the central parts of veins, commonly overlying or intergrown with manganite crystals. Jasche (1838) noted "large and excellent" calcite crystals from the manganese ore veins, as well as attractive specimens showing acicular calcite crystals sprinkled on and between manganite crystals. The color of these calcite crystals is not specified, but quite likely they are gray or black. Zincken (1825) described Ilfeld calcite tinted by inclusions of manganese oxides which the old miners called Mangankalk. Jasche (1838) mentioned specimens showing pyrolusite pseudomorphs after large calcite crystals (see under Pyrolusite), as well as gray pyrolusite pseudocrystals covered by a later generation of calcite (Jaschke, 1838). Siemroth (1990) writes that scalenohedral calcite crystals to 10 cm long were found on the old mine dumps at some time or times after mining ended in 1922.

Cryptomelane [K.sub.[1-1.5]][([Mn.sup.4+],[Mn.sup.2+]).sub.8][O.sub.16]

Cryptomelane, described formally as a species in 1982, has a name which comes from the Greek words for "hidden" and "black," since in practice it is often hard to distinguish from other black, massive manganese oxides with which it mixes intimately (www.mindat.org, 2010). Some earthy black masses of manganese oxide ore mined about 175 years ago at Ilfeld showed hardened, reniform surfaces (Jasche, 1838) typical of cyptomelane.

Groutite [alpha]-MnO(OH)

Groutite, an orthorhombic trimorph of (monoclinic) manganite and feitknechtite, is a rare species known in good specimens chiefly from the Iron Range of Minnesota (in 1980 some superb specimens were collected in the Roberts mine, Cayuna Range, Crow Wing County). In January 2006, some local collectors gained temporary access to old underground workings somewhere in the Ilfeld district (see under "Collecting Manganite"), and a very few of the 300 or so fair-to-good specimens of manganite which they extracted sport black, free-standing, leafy crystals of groutite (www.manganit.de, 2010) According to Gunnar Farber (personal communication, 2008), these crystals exceptionally reach 2 cm.

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Hausmannite [Mn.sup.2+][Mn.sub.2.sup.3+][O.sub.4]

With Ohrenstock/Ilmenau (see above under Braunite), Ilfeld is the type locality for hausmannite, described in 1813 and named for J. F. L. Hausmann (1782-1859), Professor of Mineralogy at the University of Gottingen. Hausmannite was one of the more abundant manganese ore species in the Ilfeld district, occurring in gray, foliated masses and in compact masses of radiating acicular crystals. The latter specimens, resembling hematite, show a shimmering reddish color and brownish red streak. Around 1818, large, plumose aggregates of hausmannite ore of this type were found commonly, but by 20 years later they had become rare (Jasche, 1838). The ore produced in early times from irregular pods and stringers (Trumern) in the Silberbach area was chiefly hausmannite and pyrolusite (Rumscheid, 1926). In 1844 a 30 cm-thick vein of hausmannite was mined on Harzeburg (Siemroth, 1990).

Before the wonderful hausmannite specimens of the N'Chwaning and Wessels mines in South Africa began emerging in the early 1990s, the finest "classic" hausmannites came from Ohrenstock/Ilmenau and from the manganese orebody at Langban, Sweden, both localities having produced specimens showing sharp hausmannite crystals to 2 cm. Sansoni (1971) observed that, besides the manganites of Ilfeld, "only the hausmannites ... have acquired a reputation. They have been ... compared favorably with the hausmannites of Langban and Ohrenstock." Bipyramidal, pseudo-octahedral hausmannite crystals found long ago in cavities in massive ore at Ilfeld measure only around 1 cm (Jasche, 1838), but Haake et al. (1994) wrote without elaboration that hausmannite crystals to 5 cm were found rarely at Ilfeld. Hausmannite specimens showing crystals to 2 cm have been found "in the recent past," presumably on the dumps (www.manganit.de, 2010). According to Siemroth (1990), some dump specimens from post-mining times, after removal of calcite vein fillings with HCl, show tetragonal-bipyramidal hausmannite crystals to 6 mm. In 2003-2004 a dump find yielded specimens showing 3-cm hausmannite pseudomorphs after manganite (see "Collecting Manganite," below); hausmannite pseudomorphs after calcite crystals are also known from Ilfeld (www.manganit.de, 2010).

Hematite [alpha]-[Fe.sub.2][O.sub.3]

As already noted, small veins of massive red hematite also occur in the Ilfeld district, in some cases very near the manganese veins. Although the two kinds of ore veins are thought to have formed independently (the hematite veins somewhat earlier), iron oxides occur in small amounts in the manganese veins and vice versa (Rumscheid, 1926; Haake et al., 1994). No free crystals of hematite have been found in the Ilfeld district, but lustrous black concretions of globular hematite, known colloquially as Glaskopfe ("glass heads"), were occasionally found in ore dumps at the Oberen Zug ("upper course") on the northern slope of Harzeburg, where small workings once exploited iron ore veins. Some globular hematite specimens from Harzeburg reach fist size (Rumscheidt, 1926).

Hollandite Ba[([Mn.sup.4+],[Mn.sup.2+]).sub.8][O.sub.16]

Hollandite occurs rarely at Ilfeld as druses of tiny crystals in fissures in massive manganese ores, or encrusting barite (www.manganit.de, 2010).

Kaolinite [Al.sub.2][Si.sub.2][O.sub.5][(OH).sub.4]

Kaolinite (called Steinmark by the miners) is a minor constituent of the ore veins, having been found there both as pulverulent and hardened forms. Rarely it is white; much more commonly it is pink to pale red or, when suffused by manganese oxides, pale to dark gray (Zincken, 1825; Jasche, 1838).

Manganite [Mn.sup.3+]O(OH)

The mineral we know today as manganite was first identified as a manganese oxide mineral by Jean-Baptiste Louis Rome de l'Isle (1736-1790) in the first edition of his Essai de Cristallographie (1772); he called it manganaise cristallise, and noted the confusion it had caused among previous authors:
  If it one excludes Mr. Cronstedt, who called it a particular kind of
  magnesia, and Mr. Linnaeus, who categorizes it as a kind of the
  molybdenum, all the other authors have put manganese oxide among the
  iron ore minerals, though Mr. Pott is correct in saying that, when it
  is pure, it does not contain any [iron]. Mr. Sage, according to the
  assays which he made of this substance, having found [erroneously]
  that it contained 70 pounds of zinc per quintal [100 kg], concluded
  that it must be one of the richest ores of this metal. Manganese
  oxide crystallizes in clusters composed of prisms which radiate out
  from a center, like some ore minerals of antimony, with which it is
  often confused, considering its similar color, and the sooty way in
  which it stains the fingers. These prisms are oblong, tetragonal
  rhomboidal (see the crystallographic table entry no.73); they are
  like the calamine drawing shown on plate 5, figure 9, but different
  from the crystals of calamine that I have observed in that they are
  striated along to their length.


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Rome de l'Isle loaned two specimens of Ilfeld manganite from his personal collection to Fabien Gautier d'Agoty to illustrate in his Histoire Naturelle Regne Mineral (1781), the first book in the history of mineralogy to contain mineral illustrations with printed (rather than hand-painted) colors. The divergent clusters are composed of crystals that are thinner than the typical specimens familiar to collectors today, and it is easy to see why this habit of manganite was called "radiating."

In the late 1780s Ignaz von Born, the famous mineralogist in Vienna, assembled an extensive collection of minerals for one of his patrons, Miss Eleanore de Raab. His description of the contents of the collection (Born, 1790) included a fine Ilfeld manganite ("oxide de manganese cristallise"), in "glistening gray prisms having a metallic luster, rather thick and interlaced with each other."

Another early illustration appeared when Joseph Baumeister (1750-1819) illustrated a hand-colored specimen of braunstein from Thuringia (probably Ilfeld) in his 1791 book on minerals for young readers. The engraving is somewhat crude, and might actually depict a pyrolusite crystal cluster instead of a manganite.

In 1789 Werner had introduced an array of German terms based on physical appearance and habit, generally as variations of Braunsteinerz ("manganese ore"). Widenmann (1794) described strahliger ("radiating") braunstein from "Ilefeld am Hartze." Jameson (1805), in his summary of localities for the "radiating gray manganese ore" and the "foliated gray manganese ore" of Werner, lists "Ilefeld in the Hartz." Breithaupt (1823), in summarizing the manganese oxides, listed among the Ilfeld minerals what he called Weichmanganerz ("soft manganese ore"), meaning the "usual so-called gray braunstein or gray manganerz"; Schwarzmanganerz ("black manganese ore" or Werner's "black braunstein") and Glanzmanganerz ("lustrous manganese ore"). The latter he described as occurring in "wonderful rhombic-prismatic crystals," noting that Ilfeld was the only locality known to him where such fine crystals occur--an observation which is still true today.

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William Haidinger (1826) wrote in the Edinburgh Journal of Science that "Few species in mineralogy have been so incorrectly described as the ores of manganese, and, in particular, the most common one among them, the prismatoidal manganese-ore." The various black oxides and hydroxides of manganese have indeed proven difficult for professional mineralogists and casual mineral collectors alike to distinguish, as all are black, many are poorly crystallized, and their compositions can include several subordinate components (such as OH, Ba and K). And at many localities, including Ilfeld, they can be found confusingly mixed together.

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Until 1828, mineralogists customarily used the term "prismatoidal manganese ore" for manganite (Mohs, 1825; Haidinger, 1826)--considering it among other black manganese species including "pyramidal manganese ore" (hausmannite), "brachytypous manganese ore" (braunite), "prismatic manganese ore" (pyrolusite) and "uncleavable manganese ore" ("psilomelane," now discredited in favor of cryptomelane). All of these quaint-sounding terms are employed in the course of the crystallographic examinations of manganese ores by Haidinger (1826) and the chemical examinations of them by Turner (1828); but it is Turner who employs in print for the first time the now-familiar species names, including "manganite." Both writers specify that their working samples of the "prismatoidal" ore had come from Ilfeld, and were excellently crystallized; thus Ilfeld is now considered to be the type locality for manganite. More than a century later, Buerger (1936), also working with Ilfeld specimens, derived the symmetry and crystal structure of manganite, showing it to be monoclinic, not orthorhombic as had previously been believed.

[FIGURE 19 OMITTED]

Of course, most of the manganite of the Ilfeld district came in massive form and was mined from the Schalengange ("shell veins"), together with the other black manganese ores. Sansoni (1971) also mentions flat-lying aggregates of fibrous manganite crystals, with individuals to several centimeters long and only 1 to 3 mm thick. Superbly well-crystallized manganite came only from the Schlackengange ("cinder veins"), mostly in upper levels of the workings, i.e. from the Rasenlaufer ("sod runner") veins or shallow open-pit excavations, pre-eminently in Braunsteinzeche and on Monchenberg (Rumscheidt, 1926).

Ilfeld manganite crystals have been figured by a number of early mineralogists including Mohs (1824), Haidinger (1826, 1827), Kayser (1834), Levy (1837), Presl (1837), Sadebeck (1876), Groth (1878) and Zambonini (1901). Luedecke (1896) provided detailed descriptions of various Ilfeld manganite crystal habits, resolving these into four broad categories, as follows. Type I consists of columnar crystals which are simple combinations of striated {110} prism faces and flat {001} pinacoid faces. Some Type I crystals form oblique twins, with two simple prismatic crystals crossing at angles near 60[degrees]. Type II crystals are also columnar but show several different prismatic forms (including {100}, {210} and {120}) in combination which appear as parallel columns, giving a "bundled" appearance. A zone of macropyramids (including {101}, {111}, {121}, {515}, {212}, {313}, {021}, and {2.0.15}) occurs as modifications around the edges where prisms and pinacoids meet. Type III crystals have arrays of small faces in place of the simple pinacoid {001} face, forming complex, wedge-shaped terminations; some crystals of this type also form oblique twins. In some cases a single crystal may be terminated by multiple tiny chisel-shaped points (macrodomes) in an array approximating a pinacoid. A specimen of this habit was beautifully illustrated in a finely detailed steel-plate engraving by Hubert Clerget, published in Burat's Mineralogie Appliquee (1864). Type IV crystals are the most face-rich, with macropyramids predominating, and are always twinned, but are small, appearing in druses in massive manganite; individuals are equant, with dozens of forms shown by myriads of tiny faces.

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In the finest specimens, Ilfeld manganite is jet-black to steel-gray, with strong metallic luster. In matrix specimens the manganite crystals rest either on porphyrite country rock or on massive manganite; white barite and/or calcite (having been deposited later) are present only in the interstices between crystals, and as overgrowths. The largest Ilfeld manganite crystals reach 10 cm long and 2 cm in diameter, and there exist crystal plates to several tens of centimeters square, with 40 to 50 finger-long manganite crystals rising from flat bases where the vein contacted porphyrite (Siemroth, 1990).

Nsutite [Mn.sub.x.sup.2+][Mn.sub.[1-x].sup.4+][O.sub.[2-2x]][(OH).sub.2x]

Nsutite has been found, mixed with hollandite and other manganese oxide species, in a single Ilfeld specimen; tiny nsutite pseudomorphs after manganite crystals are discernible on the specimen (www.manganit.de, 2010).

Polianite

The old term "polianite" is sometimes still used to refer to pyrolusite pseudomorphs after manganite (Bayliss, 2000).

Psilomelane

Psilomelane, corresponding to Haidinger's "uncleavable manganese ore," was the name given to some dull black, sometimes reniform, massive specimens and, presumably, to whichever massive, dull black manganese ores were not instead designated "wad." Although still in widespread use among mineral collectors, "psilomelane" properly does not denote a valid species but rather a mixture of cryptomelane, romanechite, hollandite and birnessite (Bayliss, 2000). Many "psilomelane" specimens from Ilfeld are probably in large part cryptomelane.

Pyrolusite [Mn.sup.4+][O.sub.2]

Pyrolusite, sometimes referred to in early literature as "war-wickite," occurs commonly at Ilfeld, and was, with manganite, one of the two most important ore species of the district. In fact, Siemroth (1990) argues that pyrolusite may have been taken out in greater quantity than manganite during some periods in the 19th century. Drawing inferences from the old mining documents, he wrote that in 1858, apparently, the ratio of manganite to pyrolusite in extracted ores was 2:1, but that by 1877 it had become 1:2.

Typically, pyrolusite specimens from Ilfeld show feathery bundles of acicular, steel-gray crystals lining vugs in massive manganese oxides, or radiating aggregates of fibrous crystals. More interestingly, good specimens of pyrolusite pseudomorphs after manganite ("polianite") or after calcite are known from the district. The "polianite" specimens show steel-gray, commonly lustrous, columnar crystals closely resembling unaltered manganite. The calcite pseudomorphs are dull to sub-metallic gray replacements of rough-surfaced scalenohedral calcite crystals to 10 cm, alone and in groups on massive gray manganese ore, in some cases with overgrowths of a later generation of calcite (Jasche, 1838; Sillem, 1852). Such specimens may be very old: C. F. Jasche wrote in 1838 that good examples were found "several years ago" on Harzeburg. To these pseudomorphs he applied the term Afterkrystalle--leaving one to wonder just what, in the early 19th century, led a German mineralogist to borrow the English word "after" when constructing a new single-word term for pseudomorphs.

Quartz [SiO.sub.2]

Massive quartz occurs in the deeper ore veins with manganese minerals, and may be associated with barite, calcite and hematite at the deepest explored levels, where the manganese ore-bearing veins have pinched out. Only rarely is the quartz in the manganese veins clean and white; in most cases it is shot through by manganese oxides and is gray. Miners called this hard, gray vein material Mangankiesel ("manganiferous flint") (Zincken, 1825).

Ramsdellite [Mn.sup.4+][O.sub.2]

Ramsdellite has been identified on only two specimens from Ilfeld. Both show lens-shaped aggregates of black microcrystals which are ramsdellite in their cores, pyrolusite in their outer zones; for both specimens the matrix is quartz (www.manganit.de, 2010).

Rhodochrosite [MnCO.sub.3]

White, pink and brown grains of rhodochrosite were found rarely with the manganese ores of the Ilfeld-Mangan mine in Silberbachtal (Rumscheidt, 1926; Sansoni, 1971). Very rarely, rhodochrosite forms pseudomorphs after microcrystals of manganite and hausmannite (www.manganit.de, 2010).

Romanechite [(Ba,[H.sub.2]O).sub.2][([Mn.sup.4+][Mn.sup.3+]).sub.5][O.sub.10]

Druses of lustrous black microcrystals of romanechite are rarely seen coating barite in specimens from Ilfeld (www.manganit.de, 2010).

Siderite [FeCO.sub.3]

Massive siderite, much of it shot through with fine-grained manganese oxides and hematite, is a minor constituent of the gangue fillings of the ore veins (Zincken, 1825; Rumscheidt, 1926).

Wad

Earthy, dull black, mixed manganese oxides have historically been denoted by the etherially poetic term "wad." One is tempted to speculate that it was perhaps named in honor of the Danish mineralogist and mineral collector Gregers Wad (1755-1832). However, the term "black wad" first appears in Richard Kirwan's Elements of Mineralogy (1784), at which time Gregers Wad was still contemplating a career in philology and had yet to make a name for himself in mineralogy. Most likely "wad" was a Derbyshire miner's term, as that was where Kirwan's "black wad" had been found. In any case, it is now best taken, according to Bayliss (2000), as referring to a mixture of pyrolusite, manganite, cryptomelane and romanechite. Zincken (1825) mentions an ocherous "wad" mixed with siderite which was mined on Harzeburg and in Silberbach in the very early 19th century, but Rumscheidt (1926) writes that "wad" was encountered in the Ilfeld district only on Liesenberg. Given the term's imprecision, it is not surprising that there are different accounts of which sites in the Ilfeld district gave up their wads.

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COLLECTING MANGANITE

Of course, we would very much like to have first-person accounts of discoveries of major crystallized manganite specimens, and of their dispositions, during any of the active mining periods at Ilfeld--but, according to Siemroth (1990), the old documents on file in the records office at Magdeburg hold no clue to any such specimen finds, and no stories about them have turned up elsewhere.

One very early commercial reference to Ilfeld manganite specimens is an 1831 mineral dealer's catalog issued by J. Lommel's Heidelberger Mineralien-Comptoir. He offers "Manganerz, strahliges grau [= radiating gray], Ilefeld, Ilmenau, 15 kr.-10 fl." And "Mangan, Hyperoxide, Ilefeld, Ilmenau. 24 kr.-4 fl." Ten florins in those days was quite a bit of money, equal to more than an ounce of gold. It is clear that well-crystallized Ilfeld manganite specimens were highly valued if collectors were willing to pay a silver-dollar-sized gold coin for a single example.

There are also faint indications in the general literature. The early 19th-century Bergkommissar C. F. Jasche adds the following paragraph to his thorough account (1838) of the mines as they were during the 1830s:
  The author has a number of duplicates of specimens of most of the
  manganiferous minerals described above. He would be willing to let
  these go as trades or sales--for low prices--to friends of
  mineralogy.


In 1835, at a time when unusually bountiful yields of manganese ore were being won, "wonderful manganite specimens were encountered ... and were separately collected and sold, bringing in substantial proceeds" (Gaevert, 1981). This passage suggests that the Count's Mining Office itself decided, at least in that year, to supplement profits from sales of ore with profits from the sale of crystal specimens. There is no telling what quantity of specimens reached the market in this way, but the "substantial proceeds" clearly suggests that the quantity was substantial as well. Nevertheless, such enterprise by miners in their private capacities was harshly punished: the "thievery" of crystal specimens, even if the purpose was just to display them in the miners' homes, was grounds for summary dismissal (Gaevert, 1981; Liessmann, 1997), suggesting that the value of good crystal specimens was well known at that time.

An 1843 catalog of the mineral dealership of Dr. August Kranz (1809-1872) in Berlin offered "Glanzmangan" and "Braunstein," ... "im Porphyr bei Ihlefeld im Harz."

As the 19th century wore on, the reputation of the Ilfeld mines for manganite specimens flourished:
  Around 1860 ... [Ilfeld] mining people were known not so much for the
  good quality and large quantities of their ore, but for the beauty
  and size of the manganite crystals which were being found. (Gaevert,
  1981)


[FIGURE 34 OMITTED]

The passage implies that some "mining people" were keeping up an underground trade in collector specimens--nor were the Count's own agents entirely inactive in this regard. In 1892--just after the mines had closed--two zentners of "type one manganese ore" (manganite) and two zentners of "type three manganese ore" (hausmannite) were sold to the Krantz firm, by then under the direction of Dr. Friedrich Krantz in Bonn (Siemroth, 1990). That the weight was so low (for ore) and that Krantz was a mineral-specimen dealership imply that this shipment consisted not of raw ore but of collector-quality specimens.

There are no records--not even hints--of specimen discoveries during the final period of mining in 1916-1922, even though by this time the excellence of Ilfeld manganite was widely known, and even though much larger quantities of ore per year were moved in this last phase of mining than during earlier phases. We might have expected that more crystal specimens would have been found as well.

According to Sansoni (1971), mineral dealers during the 1920s typically charged from 60 to 100 Deutschmarks for a "good display specimen" of Ilfeld manganite. Given the calamitous inflation that visited Germany in that decade, it seems impossible to "translate" this into a modern-equivalent sum.

As mentioned at the beginning, the Ilfeld region has attracted myriad hikers, bikers, nature-excursionists and mineral collectors during the 88 years since mining ceased. For some decades, visitors dug freely in the old dumps, and even ventured into the few accessible shallow adits, in search of crystals (see sidebar: "Collecting manganite after 1922"). Naturally, such ventures caused disagreeable levels of environmental degradation. The diggings in old dumps on the slopes of Harzeburg, near the Braunsteinhaus and along the way of the Bergbauhistorischer Lehrpfad were sometimes extensive enough to have undermined large trees: beeches with diameters of more than 30 cm were brought down (Siemroth, 1990). The same writer comments:
  I myself have seen how collectors from the Bundesrepublik [the former
  West Germany] have "mined" the dumps hydro-mechanically by means of a
  motorized pump placed into a stream at the foot of Harzeburg. Such
  merciless proceedings against Nature don't bear thinking of!


In 2003 there was a significant dump find of specimens showing hausmannite pseudomorphs after manganite, with dull black, prismatic pseudocrystals shot through, or protruding from, massive manganese oxide matrix. A few of the specimens were marketed at the 2004 Munich Show (Moore, 2005). In 2008 another discovery on the dumps yielded a few hundred fair-to-excellent specimens showing open seams lined by bright, sharp manganite crystals, with individuals mostly around 1 cm but exceptionally to 5 cm. The matrix is massive black manganite, and there are some subhedral white barite crystals, and, on a very few of the specimens, 2-cm metallic black crystals of the rare species groutite. About 30 of the new specimens, ranging from 4 to 10 cm across, were offered at the 2008 Tucson Show (Moore, 2008). For more on these and other modern discoveries at Ilfeld, see the sidebar "Collecting Manganite after 1922."

RELATED ARTICLE: Collecting manganite at Ilfeld after 1922.

The Ilfeld locality has remained of great interest to collectors ever since active mining ended there in 1922. Before and during World War II the district was once more energetically prospected for manganese, but under the economic conditions which then prevailed a re-activation of mining was out of the question. In the 1970s and 1980s, an agency of the government of East Germany conducted an intensive reworking of the old dumps with the goal of collecting manganite specimens and selling them for foreign exchange on the international mineral market. This work went on over several years, during which time it was shown that a professional search for mineral specimens could yield lucrative results. The search took place exclusively on the old dumps, and the finds were satisfactory enough that no attempts were made to collect in the underground workings. During the time of the former East Germany the Ilfeld dumps were accessible to all collectors, and many good specimens were recovered.

Collecting at Ilfeld became more popular but also more difficult after German reunification. Large groups of collectors from West Germany and beyond descended upon Ilfeld; collectors' clubs arrived by the busloads during the summers, and on almost every weekend, 50 to 100 people were turning over the dumps--resulting in some serious accidents, which worried the local authorities. This intensive exploitation quickly exhausted the once-productive dumps, to the understandable frustration of many local collectors.

In the mid-1990s a few of these local collectors renewed their interest. They succeeded in procuring old mine maps showing extensive layouts of old shafts, adits and dumps, and with the help of these maps they pinpointed many promising workings. Over the decades and centuries the entrances to the old adits had been largely filled in, and the corresponding dumps had been obscured by forest growth. Without the old maps no overview of the mining area would have been possible. Today the traces of most of these former workings are almost invisible, although there are many overgrown dumps on the surface; a former little valley [Salzwerferbach?--Ed.], as indicated on the old maps, is entirely filled in by dump material.

For about the past 15 years a few local collectors have more or less constantly been on the hunt for minerals at Ilfeld. They have persisted in penetrating the branching system of shallow tunnels, and they have often made fine discoveries. Since it is only mineral specimens which have been sought, large underground dumps have accumulated--there is no reason to take out material containing no crystals.

The most spectacular of the recent finds took place in autumn of 2003. A large oak tree, estimated to have been 400 years old, was uprooted by a storm, and a centuries-old ore dump beneath it was revealed and rendered accessible. This was an "original" dump previously unknown to collectors. During the very cold and snowy winter, a substantial number of excellent specimens showing hausmannite pseudomorphs after manganite were collected. Hundreds of rich pieces show columnar pseudocrystals reaching 6 cm long.

In 2008 a new vein of ore was discovered, and several hundred fine manganite specimens were collected from it. In the same year, very fine groutite crystals were found, and newly discovered dumps gave up other interesting finds. Some localized dumps have been shown to contain distinctive mineral suites, not necessarily including manganite; for example, one dump was located which yielded large pyrolusite specimens, and superb pseudomorphs of pyrolusite after calcite crystals.

Collecting at Ilfeld today is legally problematic. The forest and mining authorities would like to prevent all collecting activities, and no official permission to collect may be obtained. The local mining office is responsible for the security of the old workings--but since the responsible authorities in Ilfeld have not enclosed the old dumps with a high fence, or marked them with warning signs, no such "security" has been provided.

According to general mining law in Germany, any unauthorized person who enters an old mine shaft or adit is committing "housebreaking, regardless of whether the door stands open, or whether anyone is at home, or even whether anyone resides there." Whoever collects manganite underground at Ilfeld can also be charged with theft of ore, in addition to the trespassing charge.

[ILLUSTRATION OMITTED]

Above-ground collecting is a different matter. Since the mid-1990s, with the establishment of the Harz National Park, the collecting of minerals in the Harz has generally been tightly restricted by many new regulations. Ilfeld, however, lies outside the boundaries of the Harz National Park; accordingly there is no basic legal prohibition against collecting on the dumps at Ilfeld, especially as, legally, a mine dump is not a forest floor, and therefore cannot fall within the jurisdiction of the forest administration. The forestry office is certainly not pleased when people collect on the dumps, but it lacks jurisdiction, and, as mentioned, no mining agency has provided security for the dumps. There are in Germany many places marked by warning signs that read "trespassing forbidden by the mining police"--but in this case there are no mining police, and the municipal police are not responsible for enforcing regulations against collecting.

by Gunnar Farber

(translated by Thomas Moore)

ACKNOWLEDGMENTS

My thanks to Wendell Wilson for assistance with the early mineralogical references and dealer catalogs (nearly all of them found in the extraordinary Mineralogical Record Library), for the translations of the Rome de l'Isle and Born descriptions of manganite, and for gathering most of the illustrations and preparing the maps. Thanks also to Gunnar Farber for providing the sidebar with its updated account of collecting at Ilfeld.

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Thomas P. Moore

2709 E. Exeter Street

Tucson, Arizona 85716

tpmoorel@cox.net
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