BITOWNITE
BITOWNITE See “PLAGIOCLASE”
BERTRANDITE
BERTRANDITE Bertrandite – Be4Si2O7(OH)2 – is a rarer (or less recognized!) sorosilicate, an alteration of beryl in Be-rich granitic pegmatites. It is the second most important Be ore, after beryl. It forms crystals with a maximum length of 5 cm. It may contain Fe, Ca, and Al. There is a colloidal vitreous variety. It is […]
BADDELEYITE
BADDELEYITE Baddeleyite – ZrO2 – is a rare oxide. It constitutes a Zr ore and has great applications in geochronology. Caldasite (or zirkite) is a rock composed of zircon and baddeleyite, a mixture of 25% zirconium oxide and 75% zirconium silicate, initially identified in Poços de Caldas (MG). It is an important zirconium ore, radioactive, […]
BERYL
BERYL Beryl – Be3Al2(Si6O18) – is a cyclosilicate that typically occurs in granitic pegmatites, being an important beryllium ore. Macroscopically, beryl, when massive and light in color, can easily be confused with several other minerals typical of pegmatites, including quartz and feldspars. Occurring in pegmatites, beryl can form crystals of gigantic dimensions. The largest crystal, […]
BASTNÄSITE
BASTNÄSITE Bastnäsites are rare carbonates that form rare earth element (REE) ores. The Bastnäsite Group consists of: bastnäsite-(Ce) – (Ce(CO3)F),bastnäsite-(La) – (La(CO3)F),bastnäsite-(Nd) – (Nd(CO3)F),bastnäsite-(Y) – (Y(CO3)(OH)),hydroxylbastnäsite-(Ce) – (Ce(CO3)(OH)),hydroxylbastnäsite-(Nd) – (Nd(CO3)OH) andthorbastnäsite-(Ce) – (ThCa(CO3)2F2.3H2O). The physical properties vary little among the members. It is not possible to differentiate the members of the Group under a microscope.The […]
BAUXITE
BAUXITE Bauxite is a rock composed of the minerals diaspore – α-AlO(OH), boehmite – γ-AlO(OH) and gibbsite – Al(OH)3, mixed with the iron oxides goethite and hematite, with the clay mineral kaolinite and, in small amounts, anatase – TiO2 and other minerals. Bauxite is the main aluminum ore and lateritic bauxites (siliceous bauxites) are distinguished […]
BIOTITE
BIOTITE Biotite – K(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2 – is a very common phyllosilicate, occurring in igneous rocks (both intrusive and extrusive) and in metamorphic and sedimentary rocks. It is an important industrial mineral with many different applications. “Biotite” is not actually a mineral, but just a generic term that applies to minerals that make up a Series or […]