Mineralogy and Ore Textures of the Shepard MTN Iron Deposit, Iron Co., Missouri. (Geology/Geophysics Section).Dudley, M.A. and J.L. Nold. Department of Earth Science, Central Missouri State University Missouri State University is a state university located in Springfield, Missouri. It is the state's second largest university in student enrollment, second only to the University of Missouri. From 1972 to 2005, Missouri State was known as Southwest Missouri State University. . MINERALOGY AND ORE TEXTURES OF THE SHEPARD MTN IRON DEPOSIT, IRON CO., MISSOURI The St. Francois Terrane of southeastern Missouri hosts 6 major iron occurrences and over 30 minor occurrences. The Shepard Mountain Deposit represents one of the largest minor iron deposits and occurs about a mile SW of the Pilot Knob underground magnetite deposit. The ores are exposed as two northeast-trending, near vertically dipping veins, hosted by Middle Proterozoic rhyolites. Ore mineralization MineralizationThe process by which the body uses minerals to build bone structure. Mentioned in: Rickets mineralization, n the bioprecipitation of an inorganic substance. is characterized by abundant magnetite and lesser amounts of hematite with minor quartz, pyrite, chalcopyrite, maghemite?, chlorite chlorite Widespread group of layer silicate minerals composed of hydrous aluminum silicates, usually of magnesium and iron. The name, from the Greek for “green,” refers to chlorite's typical colour. , goethite goethite Widespread iron hydroxide mineral, α-FeO(OH), the most common ingredient of iron rust. In terms of relative abundance, it is second only to hematite (α-Fe2O3) among iron oxides. , and sericite. Textures indicate a complex history of oxidation and reduction. Magnetite commonly forms euhedral Euhedral crystals are those that are well-formed with sharp, easily-recognized faces. Normally, crystals do not form smooth faces or sharp crystal outlines. Many crystals grow from cooling liquid magma. aggregates and is present less commonly with colloform habit. Hematite is present as specular laths and as martitic replacement textures in magnetite. One of the unusual features of the deposit is the partial reduction of specular hematite to magnetite. Although the primary mineralization suggests similarities to the Pilot Knob under-ground and Iron Mountain deposits, the gangue mineralization in the Shepard Mountain deposit shows none of the diversity observed in these nearby larger deposits. Mineralogical and textural evidence indicates probable deposition of Fe-oxides from Si-poor hydrothermal solutions. |
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