pyrochlore Mineral oxide (Na,Ca,U)2 (Nb,Ta,Ti)2O6 (OH,F); sp. gr. 4.3–4.5; hardness 5.0–5.5; cubic; normally brown to black, green when heated; light brown streak; vitreous to greasy lustre; crystals usually octahedra or irregularly shaped grains; cleavage octahedral when present; found in granitic rocks and pegmatites, with or near alkaline rocks, and in association with zircon, apatite, and carbonatites. The calcium and sodium in the crystal lattice can be substituted with uranium, thorium, or the rare-earth elements.
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Titanite , sphene (titanite) A nesosilicate CaTiSiO4 (O,OH,F); sp. gr. 3.45–3.55; hardness 5; crystals wedge-shaped, occasionally massive; brown, grey, reddish… Zircon , zircon Mineral, ZrSiO4; sp. gr. 4.6; hardness 7.5; tetragonal; most commonly light brown or reddish-brown, but sometimes grey, yellow, or green; vitr… Rutile , rutile rutile An accessory mineral, TiO2; iron, niobium, and tantalum may also be present; sp. gr. 4.2–5.6; hardness 6.0–6.5; tetragonal; normally re… Biotite , biotite biotite An important rock-forming silicate mineral; a member of the mica group K2(Mg,Fe)6[Si3AlO10]2(OH,F)4, in which the Mg/Fe ratio is less… Quartzite , quartzite A metamorphic rock composed mainly of quartz and usually formed by the metamorphism of quartz sandstones. If deformation has accompanied me… Iron Ores , Rocks Rocks are composed of minerals, which are natural inorganic (nonliving) substances with specific chemical compositions and structures. A rock m…
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