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Pyrochlore2Nb2O6(OH,F) is a mineral group of the niobium end member of the pyrochlore supergroup. The general formula, A2B2O7, represent a family of phases isostructural to the mineral pyrochlore. Pyrochlores are an important class of materials in diverse technological applications such as luminescence, ionic conductivity, nuclear waste immobilization, high temperature thermal barrier coatings, automobile exhaust gas control, catalysts, solid oxide fuel cell, ionic/electrical conductors etc.
Spodumene is a pyroxene mineral consisting of lithium aluminium inosilicate, LiAl(SiO3)2, and is a source of lithium. It occurs as colorless to yellowish, purplish, or lilac kunzite (see below), yellowish-green or emerald-green hiddenite, prismatic crystals, often of great size. Single crystals of 14.3 m (47 ft) in size are reported from the Black Hills of South Dakota, United States.
Cassiterite is a tin oxide mineral, SnO2. It is generally opaque, but it is translucent in thin crystals. Its luster and multiple crystal faces produce a desirable gem. Cassiterite was the chief tin ore throughout ancient history and remains the most important source of tin today.
Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver.
Autunite (hydrated calcium uranyl phosphate), with formula Ca(UO2)2(PO4)2·10–12H2O, is a yellow-greenish fluorescent phosphate mineral with a hardness of 2–2+1⁄2. Autunite crystallizes in the orthorhombic system and often occurs as tabular square crystals, commonly in small crusts or in fan-like masses. Due to the moderate uranium content of 48.27% it is radioactive and also used as uranium ore. Autunite fluoresces bright green to lime green under UV light. The mineral is also called calco-uranite, but this name is rarely used and effectively outdated.
Boehmite or böhmite is an aluminium oxide hydroxide mineral, a component of the aluminium ore bauxite. It is dimorphous with diaspore. It crystallizes in the orthorhombic dipyramidal system and is typically massive in habit. It is white with tints of yellow, green, brown or red due to impurities. It has a vitreous to pearly luster, a Mohs hardness of 3 to 3.5 and a specific gravity of 3.00 to 3.07. It is colorless in thin section, optically biaxial positive with refractive indices of nα = 1.644 - 1.648, nβ = 1.654 - 1.657 and nγ = 1.661 - 1.668.
Samarskite is a radioactive rare earth mineral series which includes samarskite-(Y), with the chemical formula (YFe3+Fe2+U,Th,Ca)2(Nb,Ta)2O8 and samarskite-(Yb), with the chemical formula (YbFe3+)2(Nb,Ta)2O8. The formula for samarskite-(Y) is also given as (Y,Fe3+,U)(Nb,Ta)O4.
The mineral group tantalite [(Fe, Mn)Ta2O6] is the primary source of the chemical element tantalum, a corrosion (heat and acid) resistant metal. It is chemically similar to columbite, and the two are often grouped together as a semi-singular mineral called coltan or "columbite-tantalite" in many mineral guides. However, tantalite has a much greater specific gravity than columbite (8.0+ compared to columbite's 5.2). Iron-rich tantalite is the mineral tantalite-(Fe) or ferrotantalite and manganese-rich is tantalite-(Mn) or manganotantalite.
Lithiophilite is a mineral containing the element lithium. It is lithium manganese(II) phosphate with chemical formula LiMnPO4. It occurs in pegmatites often associated with triphylite, the iron end member in a solid solution series. The mineral with intermediate composition is known as sicklerite and has the chemical formula Li(Mn,Fe)PO4). The name lithiophilite is derived from the Greek philos (φιλός) "friend," as lithiophilite is usually found with lithium.
Thorianite is a rare thorium oxide mineral, ThO2. It was originally described by Ananda Coomaraswamy in 1904 as uraninite, but recognized as a new species by Wyndham R. Dunstan. It was so named by Dunstan on account of its high percentage of thorium; it also contains the oxides of uranium, lanthanum, cerium, praseodymium and neodymium. Helium is present, and the mineral is slightly less radioactive than pitchblende, but is harder to shield due to its high energy gamma rays. It is common in the alluvial gem-gravels of Sri Lanka, where it occurs mostly as water worn, small, heavy, black, cubic crystals. The largest crystals are usually near 1.5 cm. Larger crystals, up to 6 cm (2.4 in), have been reported from Madagascar.
Polycrase or polycrase-(Y) is a black or brown metallic complex uranium yttrium oxide mineral with the chemical formula (Y,Ca,Ce,U,Th)(Ti,Nb,Ta)2O6. It is amorphous. It has a Mohs hardness of 5 to 6 and a specific gravity of 5. It is radioactive due to its uranium content. It occurs in granitic pegmatites.
Fergusonite is a mineral comprising a complex oxide of various rare-earth elements. The general chemical formula of fergusonite is (Y,REE)NbO4, where REE = rare-earth elements in solid solution with Y. Yttrium is usually dominant (the mineral in this case being referred to as fergusonite-(Y)), but sometimes Ce or Nd may be the major rare-earth component (in fergusonite-(Ce) and fergusonite-(Nd), respectively). The other rare-earth elements are present in smaller amounts, and tantalum sometimes substitutes for some of the niobium. There are Fergusonite-beta-(Nd), Fergusonite-beta-(Y), Fergusonite-beta-(Ce) forms too, but they are classified as 4.DG.10 in the Nickel–Strunz system. The mineral has tetragonal crystal symmetry and the same structure as scheelite (calcium tungstate, CaWO4), but can be metamict (amorphous) due to radiation damage from its small content of thorium. It is found as needle-like or prismatic crystals in pegmatite. It was named after British politician and mineral collector Robert Ferguson of Raith (1767–1840).
Bismutite or bismuthite is a bismuth carbonate mineral with formula Bi2(CO3)O2 (bismuth subcarbonate). Bismutite occurs as an oxidation product of other bismuth minerals such as bismuthinite and native bismuth in hydrothermal veins and pegmatites. It crystallizes in the orthorhombic system and typically occurs as earthy to fibrous masses.
Clarkeite is a uranium oxide mineral with the chemical formula(Na,Ca,Pb)
2(UO
2)
2(O,OH)
3 or (Na,Ca,Pb)(UO
2)O(OH)•0-1H
2O.
Microlite was once known as a pale-yellow, reddish-brown, or black isometric mineral composed of sodium calcium tantalum oxide with a small amount of fluorine. Its chemical formula is(Na,Ca)2Ta2O6(O,OH,F). Today it is a name of a group of oxide minerals of a similar stoichiometry having tantalum prevailing over titanium and niobium. The microlite group belongs to a large pyrochlore supergroup that occurs in pegmatites and constitutes an ore of tantalum. It has a Mohs hardness of 5.5 and a variable specific gravity of 4.2 to 6.4. It occurs as disseminated microscopic subtranslucent to opaque octahedral crystals with a refractive index of 2.0 to 2.2. Microlite is also called djalmaite, but both names are now obsolete.
Neptunite is a silicate mineral with the formula KNa2Li(Fe2+, Mn2+)2Ti2Si8O24. With increasing manganese it forms a series with mangan-neptunite. Watatsumiite is the variety with vanadium replacing the titanium in the formula.
Hydrokenoelsmoreite is a hydrous tungsten oxide mineral with formula □2W2O6(H2O). Hydrokenoelsmoreite is a colorless to white, translucent isometric mineral. It has a Mohs hardness of 3, exhibits no cleavage and has a splintery fracture. It has a vitreous to adamantine luster. It is optically isotropic with an index of refraction of n = 2.24.
Loparite-(Ce) is a granular, brittle oxide mineral of the perovskite class. It is black to dark grey and may appear grey to white in reflected light on polished thin section with reddish brown internal reflections. It has the chemical formula of (Ce,Na,Ca)(Ti,Nb)O3. Nioboloparite is a variation of Loparite-(Ce) containing niobium.
Wodginite is a manganese, tin, tantalum oxide mineral with the chemical formula Mn2+(Sn,Ta)Ta2O8. It may also include significant amounts of niobium.
Ixiolite is an accessory oxide mineral found in granitic pegmatites. It is an oxide with the general chemical formula (Ta,Nb,Sn,Mn,Fe)4O8 or (Ta,Mn,Nb)O2.
References
- ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID 235729616.
- ↑ "Tantite mineral information and data". Mindat.org. Retrieved 2011-11-01.
- ↑ "Tantite Mineral Data". Webmineral.com. Retrieved 2011-11-01.
- Wisconsin minerals Accessed March 31, 2006.
- American Mineralogist data sheet PDF Accessed March 31, 2006.