psilomelane
psilomelane A hydrated manganese oxide with the possible formula Ba3(Mn2+Mn74+) O16(OH)4; sp. gr. 3.7–4.7; hardness 5–6; grey-black; sub-metallic or earthy lustre; massive, botryoidal; occurs as a precipitate in secondary manganese deposits and may be worked commercially for manganese.
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Uraninite , uraninite (pitchblende) Mineral, UO2; sp. gr. from 8.5 when massive to 10 for unaltered crystals; hardness 5–6; cubic; it is brownish-black or grey-b… wolframite , wolframite Ore mineral for tungsten, with the formula (Fe,Mn)WO4; sp. gr. 7.0–7.5; hardness 5.0–5.5; monoclinic; grey-black to brownish-black; browni… Chalcopyrite , chalcopyrite
chalcopyrite (copper pyrites) Most common copper mineral, CuFeS2; sp. gr. 4.1–4.3; hardness 3.5–4.0; tetragonal; brass-yellow, often wit… Speculum , speculum •amalgam • Targum • begum •Brigham • lingam • ogham • sorghum •Nahum • Belgium • dodgem •Brummagem • stratagem • Rackham •Malcolm • Ascham •… Commercial Metals Company , 7800 Stemmons Freeway
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Public Compa… pyrolusite , pyrolusite Common manganese mineral, MnO2; sp. gr. 4.5–5.0; hardness 5–6 for crystals, decreasing to 2 when massive; tetragonal; black to bluish-grey…
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psilomelane