stannite
stannite Comparatively rare mineral, Cu2FeSnS4; sp. gr. 4.3–4.5; hardness 3–4; tetragonal; steel-grey with an olive-green tinge on fresh surfaces, which become yellowish on exposure; black streak; metallic lustre; crystals rare, cubes or tetrahedra, but normally the grains are irregular or massive; occurs in hydrothermal tin-ore deposits and in association with cassiterite, chalcopyrite, and wolframite, also in stanniferous sphalerite–galena ores, and associated with sphalerite, pyrrhotite, and galena.
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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… Pyrrhotite , pyrrhotite Mineral, FeS; sp. gr. 4.6–4.7; hardness 3.5–4.5; hexagonal; bronzeyellow but darkens rapidly to reddishbrown on exposure; greyish-black st… 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… pentlandite , pentlandite An iron and nickel sulphide, with the formula (FeNi)9S8, and the main ore mineral for nickel; sp. gr. 4.5–5.0; hardness 3–4; cubic; light… Rare-earth Metals , rare-earth metals
rare-earth metals
rare-earth metals, in chemistry, group of metals including those of the lanthanide series and actinide series and… Periodic Table Of The Elements Chromium , chromium (krō´mēəm) [Gr.,=color], metallic chemical element; symbol Cr; at. no. 24; at. wt. 51.9961; m.p. about 1,857°C; b.p. 2,672°C; sp. gr. about…
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stannite