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Secondary minerals of the Mazarron-Aguilas mining district, Murcia Province, Spain.

Three small prospects in the Mazarron-Aguilas mining district--the Dolores prospect near Pastrana village, the La Atalaya prospect at the La Crisoleja site, and the La Umbria de Ramonete Valley prospect in the Lomo de Bas Mountains (all in Murcia Province, southeastern Spain)--have produced well-crystallized copper arsenates and associated secondary minerals. Outstanding among these are the new mineral cobaltarthurite for which the Dolores prospect is the type locality, world-class specimens of lavendulan, one of the first world occurrences of zalesiite, rare yukonite specimens and, perhaps, some future new mineral species currently under study.


At the beginning of the 1990's, a specimen labeled as "aurichalcite" from Pastrana (Murcia) was handed to one of the authors (BSB). Its habit, color and association with other copper arsenates suggested that the specimen could be lavendulan, and an EDS qualitative analysis at the Mining School of Madrid in 1992 confirmed the identification.

Subsequent studies at the Dolores prospect showed abundant lavendulan, associated with some copper arsenates and other secondary minerals. Investigations of other copper prospects in the area were conducted, and one small prospect in the Umbria de Ramonete valley was found also to produce lavendulan, as small electric-blue crystals similar to the Dolores specimens. These lavendulan crystals, better formed than the Dolores crystals, were found in a jasperoid rock at the entrance to the portal. In addition, an extensive suite of secondary minerals from the Umbria de Ramonete occurrence has been collected and studied. Investigations have also been conducted at the Atalaya copper mine, where copper arsenates are found, but no lavendulan.

One early description of these copper prospects and their secondary minerals was written for the Grupo Mineralogista de Madrid (1994); further references are found in Muelas et al. (1996), but no analytical identifications have thus far been reported. In the present paper a complete description of the secondary mineralogy of these mines is presented.


The southeastern part of Spain is among the most intensely mineralized regions of Europe, with a great variety of ore-forming environments containing primarily Pb-Zn-Ag ores. The most important economic districts from north to south are: Sierra de Cartagena (La Union), Mazarron, Aguilas and Sierra Almagrera. Mining in some of these Pb-Zn-Ag deposits was economically very important as long ago as the pre-Roman period (Villar and Egea, 1990; Rolandi, 1993; Ramallo and Berrocal, 1994). In the Mazarron-Aguilas district, the first documented mines date from 1587 (Gonzalez, 1832), when Juan Bautista Genoves got permission from the Government to work several argentiferous pedreras (gravel dumps) in Mazarron village; probably these were ancient Roman dumps of Pb-Ag ores or slags.

In 1688, the King of Spain gave Francisco de Leiva permission to work a silver mine at Mazarron. However, the major mining activity in this district was developed in the nineteenth century; in 1840 there were more than 200 shafts and galleries at Mazarron, and in 1843 40,670 quintales of lead minerals (one quintal is about 46 kg) and 96,849 marks of silver (one mark is about 230 g) were shipped from Aguilas harbor (Madoz, 1842-1850). Silver-lead mining increased between these times and 1860, especially in the Lomo de Bas (Aguilas) mines and in the Mazarron mines. During this period these lead/zinc deposits were the most productive in Spain (Villar and Egea, 1990).

Other mineral deposits in the Mazarron-Aguilas area have also been economically important. Mining of the alum (alunite) deposits of San Cerro de Cristobal began in 1462, when the King of Spain granted a license for working these mines to the Marqueses of Villena and Los Velez. The alum mining was intensively developed in the sixteenth century. These mining works led to an increase in population, and King Philip II promoted Mazarron village to the "Villa" category, naming it Villa de las Casas de los Alumbres of Mazarron (village of the houses of the alum) (Madoz, 1842-1850).

In 1853, rich iron and silver veins were discovered in Lomo de Bas (Aguilas), initiating the Carmen and La Cruz mines. Soon other large iron deposits were discovered in the Mazarron area, sometimes including small masses of lead carbonates, silver halides and antimony oxides (Villar and Egea, 1990).

However, copper mining was never of much importance. In the middle of the nineteenth century some small copper prospects developed in the course of a search for silver-rich copper sulfosalts; several claims of minor importance are registered between 1842 and 1860 in this district (Villar and Egea, 1990). But the scarcity of primary mineralization and the dissemination of the ores limited development to small prospects and drifts.

Besides the three copper prospects examined here, a few other small prospects are located between Mazarron and Aguilas; these include Morra Blanca, Sierra de las Moreras (SW of Mazarron), Sierra de la Carrasquilla and Calnegre. Copper is usually associated with the iron deposits of Sierra de Enmedio and Sierra de la Almenara, northwest to northeast of Aguilas. Of interest to collectors are the chrysocolla pseudomorphs after malachite from Morra Blanca, and the very nice short-prismatic malachite crystals, elongated on [001] and twinned on {100}, from Almendricos, Sierra de Enmedio, associated with cuprite, calcite and goethite.

By the beginning of the twentieth century, iron mining had stopped. The alum mines were definitively closed in 1953, the lead-zinc mines of Aguilas ceased working in the 1960's, and mining activities in the lead-zinc deposits of Mazarron stopped in 1969.


The Mazarron-Aguilas mining district is situated in southeastern Spain, in the eastern part of the Cordillera Betica (Betic Mountains or Betic Range). Geologically the region is known as the Betic Zone, a complex structural framework created by the relative movements of the African and European plates since the late Mesozoic. The Betic Zone may be divided into two major parts: the external and internal zones. The external zone is composed of folded and faulted rocks generally unaffected by Alpine-age metamorphism; the internal zone is characterized by a nappe structure with a very complex tectonic framework, with superimposed tectonic-stratigraphic terrains ranging from lower Paleozoic to Lower Triassic in age. A carbonate terrain of Middle to Upper Triassic age overlies the basement. Cretaceous to Cenozoic subduction-related compression, an effect of the collision of the African and European plates, was followed by Miocene postcollision extension. In the southeastern Betic Zone, as a consequence of this extension, volcanism produced a calc-alkaline belt of basalt to rhyolite rocks. Finally there was a period of widespread hydrothermal activity and associated polymetallic mineralization (Fontbote and Vera, 1983; Arribas and Tosdal, 1994).

The Betic internal zone consists of three major superimposed, deformed allocthonal tectonostratigraphic complexes: the Nevado-Filabride, the Alpujarride and the Malaguide Complexes (the latter not cropping out in this area).

The Nevado-Filabride Complex represents the core of the Betic Zone, with its oldest rocks; it is a product of multiple metamorphism. A high-pressure, low-temperature metamorphic event erased all evidence of prior alpine metamorphism. The lower part of the Complex is autochtonous, its rocks consisting mainly of quartzites and of graphite-bearing, almandine-bearing and chloritoid-bearing schists. The upper Nevado-Filabride rocks are allochthonous and more lithologically varied; they include mica schists with kyanite and staurolite, interlayered mafic metavolcanic rocks, gneisses formed from felsic volcanic rocks, quartzites, and calcite and dolomite marbles. The Alpujarride Complex has two major units. A thick lower part consists mainly of almandine-bearing mica schists, quartzites and phyllites, and an upper, carbonate part consists of limestones and dolostones, with some interbedded evaporites and mudstones.

According to the study of geological relations and Pb- isotope ranges by Arribas and Tosdal (1994), two main periods of base metal and precious metal mineralization may be distinguished in southeastern Spain. The older period produced F-Pb-Zn-Ba stratabound deposits in a Triassic carbonate platform of the paleo-Tethys Ocean, these rocks now forming the upper Alpujfirride complex. The younger period, related to hydrothermal circulation from the Miocene calc-alkaline volcanic belt, includes some Pb-Zn-(Ag-Cu-Au) and Au-(Cu-Te-Sn) epithermal vein deposits formed in volcanic rocks; it also includes Pb-Zn-Fe-Ag-(Ba-Cu-Sn-Sb) hydrothermalvein and strata-bound deposits formed in Paleozoic to Triassic clastic and carbonate rocks of the Alpujarride and Nevado-Filabride complexes, in Tertiary sediments, and in volcanic rocks of the calc-alkalic volcanic belt. The last type of deposit is found at Sierra de Cartagena, Mazarron, Aguilas and Sierra Almagrera (the type locality for jarosite and ferberite), along a narrow band parallel to the coast of the Mediterranean Sea.

In the Mazarron-Aguilas district the hydrothermal ores form a stock-work, mainly within intensely altered volcanic and subvolcanic rocks, with abundant alunite and jarosite. The deposits are hosted locally by Paleozoic mica schist and carbonates of the Nevado-Filabride Complex as well as by mica schist of the Alpujarride Complex. The Dolores and La Atalaya prospects are located in the Nevado-Filabride Complex, while the Umbria de Ramonete is located in the Alpujarride Complex.

The Pb-isotope studies of Arribas and Tosdal (1994) have shown the common origin of all the veins and strata-bound polymetallic Pb-Zn-Fe-Ag-(Ba-Cu-Sn-Sb) hydrothermal vein deposits, regardless of the nature of the host rocks. Furthermore, these studies have shown that the Pb source is not the remobilization of the Triassic-age F-Pb-Zn-(Ba) deposits of the earlier hydrothermal period; rather, the Pb appears to have originated in larger bodies intruding at depth into Paleozoic-age metasedimentary rocks. Local intrusions, as subvolcanic necks and dikes, would be too small to have produced the Pb-isotope range noted in these polymetallic deposits.

The genetic model, according to these authors, involves pervasive circulation of hydrothermal fluids through the upper crust, enhanced by a good plumbing system created by deep regional faults. Closer to the paleosurface, intensive fracturing, as well as vertical repetition of reactive carbonate levels, provided appropriate structural and lithological sites for mineralization. Finally, the formation of complex hydrothermal ores and metallic deposits may be favored locally by several physiochemical variables, e.g. changes in temperature and pressure conditions, pH and oxidation states, as well as interactions with cool meteoric water, lithological interactions, etc.

For the polymetallic mineralization area of Aguilas and Sierra Almagrera, Morales and Fenoll (1992) describe several stages of mineral formation. A first stage with chalcopyrite and sphalerite as the main minerals, and less abundant pyrite and arsenopyrite, was followed by a second stage with pyrrhotite and Bi, Fe, Ni and Co, S-As minerals. Galena and bournonite, in addition to sphalerite II and pyrite II, were the last minerals formed before supergene processes began.

In the small copper prospects that we have examined, the primary mineralogy is poorly known because strong supergene processes have masked it. We have only observed the primary species chalcopyrite and tennantite ([[Cu.sub.9.48][Fe.sub.1.50][Ag.sub.0.92] [Zn.sub.0.32]]-[[As.sub.3.56][Sb.sub.0.25][P.sub.0.05]][S.sub.13]) for a total of 99.48 percent of the weight, in a La Atalaya specimen. Other primary minerals once present are now inferable only from replacement textures, because the oxidation has been complete. The primary mineralization was probably Cu-Fe-rich S-As minerals with very minor Zn, Bi, Co and Ag, much as in the larger polymetallic deposits of Mazarron, Aguilas and Sierra Almagrera. The mineralization in the copper prospects of Mazarron and Aguilas thus closely resembles the earlier stages as described by Morales and Fenoll (1992), but without the later galena stage. Because of the abundance of As and S minerals, we can suppose the presence of arsenopyrite and pyrite in the primary stage of the mineralization, together with chalcopyrite, tennantite and minor Sb, Bi, Ni, Co and Ag-beating sulfides. However, our principal interest is in the intense supergene mineralization developed in these copper prospects, since it is responsible for the abundant secondary minerals described in this study.

The Dolores, the most representative deposit, shows supergene mineralization in a small, mineralogically zoned lens of only about 10 x 2 x 0.2 meters. Whereas jarosite and iron arsenates are more abundant in the central part of the lens, copper minerals, especially copper carbonates and conichalcite, occur predominantly in the peripheral zone.

The Umbria de Ramonete prospect displays a very similar mineralogy, suggesting a mineralizing process similar to that which operated at the Dolores deposit; however, copper-beating and silver-bearing minerals have not been found at Ramonete, carbonate minerals are scarce there, and sulfates are more common.

At the La Atalaya mine the ore is disseminated through small faults and fissures. The supergene processes operating here were not as intense as in the other mines, and sometimes lenses of unaltered tennantite, rimmed by chenevixite and other arsenic minerals, remain.


Identification of the different mineral phases was accomplished using selected micro-samples, and further examination was done by scanning electron microscopy (SEM). Initial qualitative data were obtained by means of energy-dispersive spectrometry (EDS), and supplementary X-ray diffraction (XRD) patterns were obtained for positive identification where necessary. EPMA (WDS) quantitative analyses were made for micro-samples mounted in epoxy, after a careful polishing, using a Jeol JXA-8900M electron microprobe at the Universidad Complutense (Madrid), operating at 15 Kv and 20 nA, with a beam width of between 2 and 5 microns, and a Cameca electron microprobe at Barcelona University (for the cobaltarthurite and yukonite analyses).

Below are described, in alphabetical order, the most interesting secondary minerals of the Mazarron-Aguilas prospects. Table 1 is a complete list of the secondary minerals found there to date.

Alunite-Jarosite group minerals

According to Jambor (1999), Stoffregen et al. (2000) and Dutfizac et al. (2000), the alunite supergroup consists of more than 40 mineral species with a general formula D[G.sub.3][(T[O.sub.4]).sub.2] [(OH,[H.sub.2]O).sub.6]. D sites are occupied by monovalent cations such as K or Na, or divalent cations such as Ca and Sr. G sites are mainly Al or [Fe.sup.3+], and T are [S.sup.6+], [As.sup.5+], [P.sup.5+] and sometimes subordinate [Si.sup.4+]. Because the substitutions K-Na, and Al-[Fe.sup.3+] form a continuous series, we prefer to consider these minerals together.

In the Mazarron-Aguilas district, and especially in the Dolores and Umbra de Ramonete prospects, the alunite-group minerals are very common, forming wide, pale brown to yellowish veins. The vein fillings are composed of loose crystals, from a few micrometers to 1 mm in size, of rhombohedral habit and of a pale to dark brown colon Sometimes the crystals show an idiomorphic habit, and a compositional zoning can be observed by BEI, with an inner zone of Na/K > 1 (natrojarosite) and an outer zone with Na/K < 1 (jarosite). Sometimes a second generation of K-dominant jarositealunite has grown on these idiomorphic crystals.

Alunite, natroalunite, jarosite, natrojarosite and perhaps some hydronium jarosite are all present at Mazarron, and the silver content in these minerals is less than 0.2% by weight.

Aragonite CaC[O.sub.3]

Crusts of white aragonite, in fibers up to 1 cm, deposited from supergene waters, are common at the Dolores prospect. Prismatic to acicular monocrystals are less common. Often aragonite partially covers large, bright green conichalcite plates, making very nice color-contrasting specimens.

Arseniosiderite [Ca.sub.2][Fe.sup.3+.sub.3] [(As[O.sub.4],P[O.sub.4]).sub.3][O.sub.2]*3[H.sub.2]O

Arseniosiderite appears as brown to golden yellow platy crystals forming the matrix for chlorargyrite and several arsenates. Epimorphs/pseudomorphs of arseniosiderite after siderite and overgrowths of arseniosiderite on the edges of pharmacosiderite crystals were also observed at the Dolores prospect. At the Umbria de Ramonete prospect arseniosiderite is found rarely with pharmacosiderite.

Arsenocrandallite (Ca,Sr)[Al.sub.3][(As[O.sub.4], P[O.sub.4]).sub.2][(OH).sub.5]*[H.sub.2]O

Arsenocrandallite from the Dolores prospect was identified by EDS and XRD, as fibrous spherules of radiating crystals to 1 mm. The translucent, gray-white to pale blue globules consist of clusters of crystals tabular on {0001}. Frequently it is found with siderite, lavendulan, conichalcite and arseniosiderite.

Arsenogoyazite (Sr,Ca,Ba)[Al.sub.3][(As[O.sub.4], P[O.sub.4]).sub.2][(OH,F).sub.5]*[H.sub.2]O

Small white globules, up to 0.1 mm, from the Dolores prospect have been identified by EDS and XRD as an Sr > Ca member of the arsenogoyazite-arsenocrandallite series. Arsenogoyazite may be one of the last minerals to form, since it commonly overlies yukonite. It has also been found overlying the larger arsenocrandallite globules.

Arthurite [Cu.sup.2+][Fe.sup.3+.sub.2][(As[O.sub.4], P[O.sub.4],S[O.sub.4]).sub.2][(O,OH).sub.2]*4[H.sub.2]O

Arthurite, as long-prismatic bright green crystals, was found in a single specimen from the Dolores prospect, identified by EDS. The crystals, up to 0.1 mm, occur isolated and in clusters on pharmacosiderite cubes.

Atacamite (?) [Cu.sup.2+.sub.2]Cl[(OH).sub.3]

A mineral closely approximating atacamite--paratacamite in composition (Table 3) appears in backscattered electron images (BEI) as small inclusions in brochantite aggregates from the Umbria de Ramonete prospect. The very small quantity of the material and its close association with brochantite make confirmation by XRD impossible. The atacamite phase appears to have formed prior to brochantite.

Azurite [Cu.sup.2+.sub.3][(C[O.sub.3]).sub.2][(OH).sub.2]

The copper carbonates malachite and azurite are widespread in the Mazarron-Aguilas district, although azurite has not been found at the Umbria de Ramonete prospect. Usually, azurite forms fine single crystals and crystal clusters covering plates of several square centimeters. Individual crystals can reach 5 mm, with an intense blue color contrasting with the pale brown matrix. Azurite can be replaced by conichalcite.

Brochantite [Cu.sup.2+.sub.4](S[O.sub.4])[(OH).sub.6]

At the Umbria de Ramonete prospect, brochantite forms rounded, prismatic, emerald-green crystals to 4 mm in size associated with lavendulan. A representative analysis is shown in Table 3. At the Dolores prospect, brochantite was found as veinlets about 1 mm across in malachite, from which it is distinguished by its darker green color. This mineral is very scarce in both prospects.

Chenevixite [Cu.sup.2+.sub.2][Fe.sup.3+.sub.2] [(As[O.sub.4]).sub.2][(OH).sub.4]*[H.sub.2]O

Chenivixite was identified by Muelas et al. (1996), without benefit of analyses, in samples from the Umbria de Ramonete prospect, as microcrystal aggregates shaped like open tulips.

At the La Atalya prospect chenevixite is a direct product of tennantite oxidation, forming as crusts and disseminated areas of alteration in tennantite (see Table 4).

At the Umbria de Ramonete prospect, chenevixite forms yellow-green to grass-green crusts and masses with olivenite, and powdery to nodular precipitates on quartz. Rarely it has been found as very small acicular individual crystals and clusters.

Chlorargyrite AgCl

Small, pale greenish to pale yellowish cuboctahedral crystals of chlorargyrite under 2 mm have sometimes been found in the Dolores prospect, perched on druses of microcrystals of arseniosiderite, jarosite, conichalcite and pharmacosiderite. Common forms are {111} and {100}; rarely, crystals are twinned on {111}. Rounded xenomorphic botryoidal crystalline masses also occur. The chlorargyrite has a low Br content (EDS).

Yellow-green chlorargyrite crystals perched on lavendulan crystal clusters make extremely fine micromount specimens.

Chrysocolla [([Cu.sup.2+,]Al).sub.2][H.sub.2][Si.sub.2] [O.sub.5][(OH).sub.4]*n[H.sub.2]O

Small concretions or pseudomorphs of pale blue chrysocolla after tyrolite were common at the La Atalaya prospect. At the Dolores prospect, chrysocolla was only observed as pseudomorphs after lavendulan.

Cobaltarthurite Co[Fe.sup.3+.sub.2][(As[O.sub.4]).sub.2] [(OH).sub.2]*4[H.sub.2]O

The Dolores prospect is the type locality for cobaltarthurite, a new mineral of the arthurite group (Jambor et al., 2002). Cobaltarthurite occurs predominantly as globular to pellet-like aggregates approximately 1 mm across, consisting of radial fibers. The color grades from straw-yellow to dark brown, although no significant compositional changes were detected within the aggregates. The mineral has also been found as veins up to 2 cm across, filling fractures in the siliceous rock. Exceptionally, cobaltarthurite appears as up to 0.5-mm tufts of divergent prismatic crystals of straw-yellow to golden yellow color. The most consistent association is with pharmacosiderite, on which the pellets or tufts of cobaltarthurite are usually implanted. More rarely, cobaltarthurite is associated with arseniosiderite and heterogenite.

Conichalcite Ca[Cu.sup.2+](As[O.sub.4])(OH)

Conichalcite is one of the later-forming minerals and the most common secondary mineral in Mazarron, principally in the Dolores prospect. At this occurrence a spectacular formation was found: a surface of about 10 [m.sup.2] completely covered with conichalcite. Some mineralogical and chemical characteristics were determined by Del Valle et al. (1995). According to his work and our research by EPMA, Ba and Na substitute weakly for Ca, and Si, P and S for As. Botryoidal conichalcite commonly grows on azurite, malachite, pharmacosiderite, arseniosiderite and lavendulan, and very frequently on olivenite, sometimes completely replacing the latter, as pseudomorphs. The pale green color may distinguish conichalcite from cornwallite (bright green), a commonly associated mineral in the Dolores and Umbria de Ramonete prospects.

Cornwallite [Cu.sup.2+.sub.5][(As[O.sub.4]).sub.2][(OH).sub.4]

Cornwallite appears as 1-mm spherules and as 2-mm to 3-mm clusters of spherules of a transparent, emerald-green color; at the La Atalaya prospect the spheres cover large surfaces, making this a significant locality for the mineral. Olivenite and tyrolite can be associated. The color contrast of green comwallite and blue azurite against a brown matrix makes for pretty micromount specimens.

In the Dolores and Umbria de Ramonete prospects, cornwallite is less common, appearing as dark green botryoidal masses and minute crystal clusters.

In this cornwallite there is minor substitution of P for As (see Table 4).

Heterogenite CoO(OH)

Botryoidal crusts and spheroids of heterogenite are relatively common at the Dolores prospect, mainly associated with arseniosiderite and less commonly with cobaltarthurite. EDS spectra of most of these samples indicate pure CoO(OH), and its XRD patterns correspond to the Heterogenite-2H polytype. Some samples, however, contain admixed manganese oxides and are shown by XRD to have poor crystallinity.

Hornesite (?) [Mg.sub.3][(As[O.sub.4]).sub.2]*8[H.sub.2]O

Hornesite was mentioned by Muelas et al. (1996) in samples from the Dolores prospect, but analytical data were not provided.

Lavendulan NaCa[Cu.sup.2+.sub.5][(As[O.sub.4]).sub.4]Cl*5[H.sub.2]O

Lavendulan is an uncommon mineral that has been found in a few localities worldwide, always as crusts or minute crystals. The superb crystals and clusters recovered at Mazarron in 1992 must be considered as perhaps the best in the world. Specimens from these localities appear to be far superior to those from other known world localities listed in Clopton and Wilson (1995), and Anthony et al. (2000) cite the largest known crystals as 3 mm.

In the Umbria de Ramonete prospect, lavendulan forms bladed to lath-like crystals to 4 mm, and radial groups to 10 mm, covering large matrix plates of jasperoid rock. Individual crystals are flattened on {010} and elongated on {001}. The typical color is electric blue on fresh surfaces and pale blue in altered crystals. Very pretty specimens of bladed, free crystals have been found in quartz cavities, together with pharmacosiderite, yukonite and olivenite needles. Other associated minerals include cornwallite, conichalcite, jarosite-natrojarosite, malachite and pharmacosiderite.

In the Dolores prospect, lavendulan appears as clusters of electric blue laths to 1 mm in druses coating cavities to several centimeters. Here the mineral is most abundant, and hundreds of thumbnail to cabinet-sized specimens have been recovered. Azurite, conichalcite, cornwallite, yukonite and rarely chlorargyrite and arsenocrandallite may be present.

A representative lavendulan analysis is shown in Table 4, showing formulae near the theoretical one without significant substitutions.

Malachite [Cu.sup.2+.sub.3][(C[O.sub.3]).sub.2][(OH).sub.2]

Acicular and bladed malachite crystals, and radial clusters of prismatic crystals to 1 mm, are frequently found in all Mazarron-Aguilas copper prospects.

Olivenite [Cu.sup.2+.sub.2](As[O.sub.4])(OH)

Olivenite occurs in all Mazarron prospects as more or less elongated prismatic crystals in different shades of green. There are no significant chemical substitutions, as can be seen in Table 4.

In the Umbria de Ramonete prospect olivenite is very abundant, usually as dark green prismatic to acicular crystals of less than 3 mm. In the goethite cavities, olivenite is found together with cornwallite and conichalcite; in the quartz cavities, it can be accompanied by phannacosiderite, lavendulan and chenevixite. Olivenite has also been found in a few specimens on scorodite-mansfieldite and yukonite.

A wider variation in crystal habit is found in the Dolores prospect. Acicular to short prismatic {001} olivenite crystals up to 3 mm and crystal clusters to 10 mm are present in the siderite cavities with azurite, and more rarely with pharmacosiderite. The crystals can be covered by a thin film of conichalcite, or even totally replaced by this mineral, making fine pseudomorphs. Olivenite is also found as radiating fibres with color zoning in shades of gray to green, or as gray to olive-green fibrous crystals of silky luster covering large fracture surfaces.

Rarely, olivenite is found at the La Atalaya prospect, in pale green prismatic crystals on cornwallite.

Parnauite (?) [Cu.sub.9][(As[O.sub.4]).sub.2] (S[O.sub.4])[(OH).sub.10]*7[H.sub.2]O

A parnauite-like mineral, apple-green to olive-green, occurs at the Dolores prospect as minute (0.1-1 mm) clusters of tabular to platy crystals with square or rectangular outline. The crystals are usually implanted on pharmacosiderite or yukonite, associated with malachite, azurite or lavendulan. The EDS spectra are very close to those obtained, by similar instrumental means, from the parnauite of Majuba Hill (Nevada, USA). The XRD spectra showed the main lines of parnauite but also other lines, which were assigned to quartz and pharmacosiderite. The very small available quantities of this mineral do not permit a definitive characterization.

Pharmacolite (?) CaHAs[O.sub.4]*2[H.sub.2]O

According to Muelas et al. (1996), small crystals of pharmacolite were found in the Umbria de Ramonete prospect, associated with chenevixite, but analytical data have not been provided, and the presence of pharmacolite seems very doubtful.

Pharmacosiderite and sodiumpharmacosiderite (K,Na)[Fe.sup.3+.sub.4][(As[O.sub.4]).sub.3][(OH).sub.4]*6-7[H.sub.2]O

As in the case of the alunite-group minerals, common cation substitutions in pharmacosiderite are Na and Ba for K, Al for [Fe.sup.3+], and minor P for As, forming several minerals (Gaines et al., 1997). Except for Ba[K.sub.-1], all these substitutions are present in pharmacosiderite from Mazarron-Aguilas. So Na[K.sub.-1] substitution (to Na/K up to 1.2) has been found, together with an important Al[Fe.sup.3.sub.-1] substitution (Table 4).

These minerals, widespread in the Mazarron-Aguilas copper prospects, form pale green to yellow crusts of idiomorphic cubes to 1 mm. At the Dolores prospect, these minerals sometimes cover the siderite and the fracture surfaces of the host rock. Pharmacosiderite is commonly overlain by arseniosiderite and sometimes replaced by yukonite.

Yellowish to greenish crusts composed of very minute (less than 0.1 mm) cubes of sodium pharmacosiderite are also common at the Dolores prospect. This sodium species appears in the late-stage crystallization and is not associated with arseniosiderite

Scorodite-mansfieldite ([Fe.sup.3+],Al)As[O.sub.4]*2[H.sub.2]O

The scorodite-mansfieldite series, probably as a complete solid solution (Gaines et al., 1997), is abundant in the Dolores and Umbria de Ramonete prospects. The minerals are difficult to recognize because they are often covered or replaced by yukonite. Scorodite-mansfieldite appears as crusts, globules or more rarely as pyramidal {111} microcrystals. The chemical analysis (Table 4) shows monovalent and divalent substitutions for K; Al for [Fe.sup.3+]; and P, S, and minor Si for As. These substitutions are similar to those in alunite-group minerals. At the Dolores prospect mansfieldite the [As.sub.6][S.sub.-5] substitution is significant.

Tyrolite Ca[Cu.sup.2+.sub.5][(As[O.sub.4]).sub.2] (C[O.sub.3])(OH)*6[H.sub.2]O

Tabular, emerald-green, pearly crystals and groups of tyrolite to 2 mm have been identified by EDS. The tyrolite is fairly common at the La Atalaya prospect, with comwallite and, less frequently, azurite.

Yukonite [Ca.sub.7][Fe.sup.11+.sub.11][(As[O.sub.4]).sub.9] [O.sub.10]*24*3[H.sub.2]O(?)

Yukonite, an amorphous arsenate compound of varying composition, is a rare mineral which has been reported previously from only four localities in the world: Tagish Lake, Yukon, Canada; Sterling Hill, New Jersey, USA; Saalfeld, Thuringia, Germany; and Redziny, Poland (Pieczka et al., 1998; Anthony et al., 2000).

At the Dolores and Umbria de Ramonete prospects, yukonite forms veinlets, spheroids or pseudomorphs, replacing scorodite or, more rarely, pharmacosiderite. Its color is reddish brown to purplered and its luster is vitreous to resinous.

The chemical composition is shown in Table 2, which also presents this composition in the form of ion contents on the basis of 9 aniomic groups, in accordance with the mineral database (2001) and the New Dana Classification of Hydrated Phosphates (2001). In the same table, the data reported by Pieczka et al. (1998) from the other localities were also included. As can be seen, all the natural yukonites fit relatively well for the ratios 9 (X[O.sub.4]) (6-7) [A.sup.2+] and (9-12) [B.sup.3+]. Other proposed formulas, such as [Ca.sub.6][Fe.sub.16][(As[O.sub.4]).sub.10] [(OH).sub.30]*23[H.sub.2]O (Jambor, 1966), [Ca.sub.3][Fe.sub.7] [(As[O.sub.4]).sub.6][(OH).sub.9]*18[H.sub.2]O (JCPDS, 1982, 1992), and [Ca.sub.2][Fe.sub.3][(As[O.sub.4]).sub.4](OH)*12[H.sub.2]O (Mandarino, 1999), deviate more widely from data from some reported localities. Probably the problem is associated with the amorphous nature of this species and the unknown role of potential substitutes for [Ca.sup.2+], [Fe.sup.3+] and As[O.sup.3-.sub.4]. A chemical characteristic of the yukonite of this district is the presence of significant copper, especially in the Dolores prospect specimens. A similar zinc content is found, however, in some analyses of Sterling Hill yukonite (Pieczka et al., 1998). Silica content is high in yukonites of this district and, according to Pieczka (op. cit.), also in Sterling Hill.

Zalesiite (Ca,Bi)[Cu.sup.2+.sub.6][(As[O.sub.4]).sub.3] [(OH).sub.6]*3[H.sub.2]O

During the course of this work, zalesiite was described from Zalesi, Czech Republic, by Sejkora et al. (1999). So the Mazarron zalesiite (found only in the Dolores prospect) is among the first world occurrences.

Zalesiite occurs as green to pale blue sprays of thin acicular crystals and radial clusters, to 3 mm, with siderite and conichalcite. Very fine specimens were collected in a limonitic gossan.

The chemical composition (Table 4) shows large substitutions in the Ca-Bi site and no REE or Y content such as was seen in the Zalesi material. Mazarron zalesiite is a solid solution between mixite and zalesiite, but because Ca > Bi it must be classified as zalesiite. A high-Ca mixite has been observed at the Gold Hill mine, Utah (Kokinos and Wise, 1993), suggesting a possible solid solution series also at Gold Hill.

Unknown # 1

This unknown mineral, a Na/Ca/Cu/(Fe/Al)-chloride-arsenate hydrate, was found at the Dolores prospect. It appears as yellow-green (Fe-rich) to pale sky blue (Al-rich) powdery crystalline crusts, which usually overlie jarosite and pharmacosiderite. Under SEM, the powder appears to consist of tabular crystals up to 20 micrometers long and less than one micrometer thick. These characteristics have impeded progress in characterization; further studies of this mineral are under way.

Unknown #2

This mineral occurs in Dolores as minute clusters of tabular to platy crystals of apple-green to olive-green color, similar to the parnauite. Its chemical composition, measured by EPMA for several different points and crystals, is near [Fe.sup.3+.sub.0.2][Al.sub.0.3][Mg.sub.0.1] [Cu.sub.3.0][Zn.sub.0.05]-([As.sub.0.8][Si.sub.0.1] [S.sub.0.1][P.sub.0.05])[O.sub.4]. The simple Cu/As ratio, close to 3, resembles the clinoclase/gilmarite ratio, but the substitutions up to 0.65 cation and the low S content is the problem. The very scarce quantity of this mineral does not permit us to make an XRD determination.

This mineral crystallized before azurite, since idiomorphic azurite crystals are implanted on it.


The Mazarron-Aguilas copper prospects contain a complex suite of K-Na-Ca-Cu-[Fe.sup.3+]-Al, with minor Bi-Co-Ag, secondary arsenate, sulfate and carbonate mineral assemblages.

In the Dolores prospect, the secondary-mineral zoning, where jarosite and iron arsenates are more abundant in the central part of the lens and copper minerals are more abundant in the peripheral zone, suggests a higher mobility of copper than of iron in the first supergene fluids, with a normally decreasing gradient of acidity from the core to the rim of the lens. This decrease in the acidity of the fluids had to be very sharp when the fluids contacted the siderite and the carbonate rocks in the external border of mineralization, producing a decrease in copper solubility and the formation of secondary copper minerals: olivenite and the carbonates azurite and malachite. Contemporaneously, scorodite, pharmacosiderite and jarosite were formed, while the bordering siderite was replaced by goethite.

After this stage an enrichment in calcium resulted from the leaching of rock generated by the acidity produced by alteration of sulfides. Arseniosiderite was deposited abundantly, and scorodite was partially replaced by yukonite. In this phase, the increase of Ca activity began to form conichalcite as epimorphs/pseudomorphs over olivenite, azurite and malachite. Zalesiite and arsenocrandallite were also formed.

A final precipitation stage was characterized by the incorporation of Cl, probably from supergene waters, so chlorargyrite, atacamite, lavendulan and an unknown Na-Ca-Cu-Fe chloridearsenate were formed.

In the Umbria de Ramonete, the mineralogical association suggests a similar geochemical process as in the Dolores deposit, although a different carbon/sulfur ratio must be expected, since carbonate is less abundant than sulfate.

A similar process is observed in La Atalaya, where chenevixite, tyrolite, cornwallite, olivenite and azurite were the first-formed secondary minerals, partially replaced thereafter by conichalcite. A final Si-rich phase, without Cl, formed chrysocolla.
Table 1. Distribution of the secondary minerals of the
Dolores, Umbria de Ramonete and La Atalaya prospects.

Mineral                    Dolores    Ramonete    La Atalaya

Alunite                      --          R            --
Aragonite                    C           --           --
Arseniosiderite              C           C            --
Arsenocrandallite            R           --           --
Arsenogoyazite               R           --           --
Arthurite                    VR          --           --
Atacamite ?                  --          VR           --
Azurite                      VC          --           VC
Brochantite                  VR          R            --
Chenevixite                  --          C            --
Chlorargyrite                R           --           --
Chrysocolla                  R           --           C
Cobaltarthurite              R           --           --
Conichalcite                 VC          C            C
Cornwallite                  C           R            VC
Heterogenite                 R           --           --
Hornesite ?                  VR          --           --
Jarosite-natroj arosite      C           VC           --
Lavendulan                   C           C            --
Malachite                    VC          R            R
Olivenite                    VC          VC           C
Parnauite ?                  VR          --           --
Pharmacosiderite             VC          C            --
Scorodite-mansfieldite       C           C            --
Sodium pharmacosiderite      C           --           --
Tyrolite                     --          --           C
Yukonite                     C           C            --
Zalesiite                    R           --           --
Unknown #1                   VR          --           --
Unknown #2                   VR          --           --

VC, very common; C, common; R, rare; VR, very rare;--not found.

Table 2. Contents of ions on the basis of 9
[(As,P)[O.sup.3-.sub.4], S[O.sup.2-.sub.4], Si[O.sup.4-.sub.4]] for
natural yukonite.

               1        2        3       4        5       6        7

Ca              5.49     5.07    4.62     5.79    5.84     4.14    4.89
Mg              0.18     0.27    0.36     0.27    0.26     0.86    0.41
Mn              0.14     0.81    0.77      --     0.15     0.03    0.00
Zn              0.17     1.11    1.17      --     0.17      --      --
Cu               --       --      --       --      --      1.29    0.09
-[M.sup.2+]     5.98     7.26    6.92     6.06    6.42     6.32    5.39

[Fe.sup.3+]    11.96     9.86    8.96    10.61    9.63    10.58    8.58
Al               --      0.45    0.50     0.53     --      0.90    0.08
-[M.sup.3+]    11.96    10.31    9.46    11.46    9.63    11.48    8.66

As              8.28     7.91    8.65     9.00    8.78     7.10    6.93
P               0.35      --      --       --     0.09     0.18    0.14
S               0.08     0.08    0.08      --     0.03     0.02    0.05
Si              0.27     1.02    0.27      --     0.09     1.71    1.85

1: Yukon, 2-3: New Jersey, 4: Saalfeld, 5: Redziny, 6: Dolores
prospect, 7: Umbria de Ramonete. 1-5 Calculated from data
reported by Pieczka et al. (1998).

Table 3. Representative electron microprobe analyses of
Mazarron-Aquilas jarosite, brochantite and atacamite.

                       Ja-I     Ja-II     Bro      Ata

[Al.sub.2][O.sub.3]    15.39     1.11     0.08     0.13
[Fe.sub.2][O.sub.3]    28.08    46.36     0.23     0.13
FeO                     --       --       --       --
MgO                     0.20    <0.01     0.01     0.83
CuO                     0.81     0.01    73.81    68.35
ZnO                     0.02     --      <0.06    <0.06
PbO                     0.01     0.16     --       --
BaO                     --       0.05     0.28     0.24
CaO                     0.09     --      <0.02     0.39
SrO                     --      <0.02     0.04     0.02
[Na.sub.2]O             0.58     0.68    <0.01     0.08
[K.sub.2]O              4.92     6.71     0.01     0.12
Si[O.sub.2]             0.19    <0.01     0.03     1.19
[P.sub.2][O.sub.5]      0.02    <0.02     0.02     0.13
[As.sub.2][O.sub.5]     0.59     0.46     0.39     0.18
S[O.sub.3]             34.12    30.84    18.94     0.38
Cl                     <0.01    <0.01     0.01    18.39
Cl_O                    --       --       --       4.35
Total                  85.52    86.38    93.85    86.21

Ja-I, Al-rich -jarosite (Dolores): [Al.sub.1.38][Fe.sup.3+.sub.1.62]

Ja-II, jarosite (Dolores): [Al.sub.0.11][Fe.sup.3+.sub.2.49]

Bro, brochantite (Umbria de Ramonete): [Fe.sub.0.01][Cu.sub.3.92]

Ata, atacamite? (Umbria de Ramonete): [Fe.sub.0.04][Cu.sub.1.66]

Table 4. Representative electron microprobe analyses of Mazarron-
Aquilas arsenates.

                      Lav      Pha      Sco      Che      Oli

[Al.sub.2][O.sub.3]   <0.01    16.06     7.30     1.83     0.18
[Fe.sub.2][O.sub.3]     --     25.50    29.63    23.81      --
FeO                    0.01      --       --       --      0.03
MgO                    0.05     0.07     0.23     0.53    <0.01
CuO                   40.20     0.27     0.45    27.58    57.79
ZnO                   <0.06     0.12     0.11    <0.06      --
PbO                              --       --      0.01      --
[Bi.sub.2][O.sub.3]     --       --     <0.04      --       --
BaO                    0.25     0.04     0.70      --       --
CaO                    5.87     0.67     0.02     0.77    <0.01
SrO                   <0.02     0.10    <0.02      --       --
[Na.sub.2]O            3.48     0.89     0.05     0.07    <0.01
[K.sub.2]O             0.13     6.46     0.02     0.07    <0.01
Si[O.sub.2]            0.01     0.02     0.23     0.31     0.06
[P.sub.2][O.sub.5]     0.23     0.05     0.13     0.24      --
[As.sub.2][O.sub.5]   45.00    40.81    49.85    33.91    39.63
S[O.sub.3]             0.05     5.63    <0.01     0.10     0.01
Cl                     3.63      --       --      0.02    <0.01
Cl-O                   0.82      --       --       --       --
Total                 98.00    96.69    88.59    89.55    97.69

                      Cor      Zal      Yuk-I    Yuk-II

[Al.sub.2][O.sub.3]    0.22     0.36     1.83      0.14
[Fe.sub.2][O.sub.3]     --       --     33.51     31.19
FeO                   <0.04     0.86      --        --
MgO                   <0.01    <0.02     1.36      0.74
CuO                   60.09    45.27     4.04      0.34
ZnO                     --       --       --        --
PbO                     --      0.04      --        --
[Bi.sub.2][O.sub.3]     --     10.74      --        --
BaO                     --      0.23      --        --
CaO                    0.23     3.59     9.19     12.47
SrO                     --       --       --        --
[Na.sub.2]O           <0.01    <0.01      --        --
[K.sub.2]O            <0.01     0.08      --        --
Si[O.sub.2]            0.07     0.02     4.10      5.17
[P.sub.2][O.sub.5]     1.74     0.20     0.53      0.44
[As.sub.2][O.sub.5]   31.68    33.36    32.30     36.38
S[O.sub.3]             0.07      --      0.04      0.13
Cl                     0.05    <0.01      --        --
Cl-O                   0.01      --       --        --
Total                 94.08    94.73    86.97     87.00

Lav, lavendulan (Umbria de Ramonete): [Mg.sub.0.01][Cu.sub.5.12]

Pha, pharmacosiderite (Dolores): [Al.sub.2.17][Fe.sup.3+.sub.2.2]

Sco, scorodite (Dolores): [Al.sub.0.33][Fe.sup.3+.sub.0.85]

Che, chenevixite (Umbria de Ramonete): [Al.sub.0.24]

Oli, olivenite (Dolores): [Cu.sub.2.11](As[O.sub.4])

Cor, cornwallite (La Atalaya): [Al.sub.0.02][Cu.sub.5.03][Ca.sub.0.02]

Zal, zalesiite (Dolores): [Al.sub.0.07][Fe.sup.2+.sub.0.12]

Yuk-I, yukonite (Dolores): For formula see table 4

Yuk-II, yukonite (Umbria de Ramonete): For formula see table 2


The authors thank A. Barahona for providing information about the Pastrana locality and for providing specimens for analysis to one of us (J. Vinals), as well as for finding the first samples of cobaltarthurite and unknown #1. Thanks also are due to the Common Services of the University of Barcelona and the Universidad Complutense (Madrid), especially to Alfredo Fernandez Larios, for providing instrumentation and assistance in the SEM/EDS, XRD and EPMA analyses. M. Gordillo provided some specimens to photograph, F. Pina made some photos and M. Oliete drew the map. Thomas Moore and Wendell Wilson of the Mineralogical Record improved the English manuscript.


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Borja Sainz de Baranda

Miami 3

28027 Madrid, Spain

Jose Gonzalez del Tanago

Departamento de Petrologia y Geoquimica

Facultad de Ciencias Geologicas

Universidad Complutense de Madrid

28040 Madrid, Spain


Joan Vinals

Departamento de Ingenieria Quimica y Metalurgia

Facultad de Quimicas

Universidad de Barcelona

08028 Barcelona, Spain.

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Date:Jul 1, 2003
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