A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than 1 cm (0.4 in) and sometimes greater than 1 meter (3 ft). Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic composition to granite. However, rarer intermediate composition and mafic pegmatites are known.
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.
Triplite is a rare phosphate mineral with formula: (Mn, Fe)2PO4(F, OH). It occurs in phosphate-rich granitic pegmatites typically as irregular brown opaque masses. Triplite was first described in 1813 for an occurrence in Chanteloube, Limousin, France. The name is from the Greek triplos for triple, in reference to the three cleavage directions. In color and appearance, it is very similar to rhodocrosite, another manganese bearing mineral. Chemically, it is also quite similar to triploidite the difference being that triplite is fluorine dominant while triploidite is hydroxide dominant.
Frank Christopher Hawthorne is a Canadian mineralogist, crystallographer and spectroscopist. He works at the University of Manitoba, Winnipeg, Manitoba, Canada, and is currently Distinguished Professor Emeritus. By combining Graph Theory, Bond-Valence Theory and the moments approach to the electronic energy density of solids he has developed Bond Topology as a rigorous approach to understanding the atomic arrangements, chemical compositions and paragenesis of complex oxide and oxysalt minerals.
Seamanite, named for discoverer Arthur E. Seaman, is a rare manganese boron phosphate mineral with formula Mn3[B(OH)4](PO4)(OH)2. The yellow to pink mineral occurs as small, needle-shaped crystals. It was first discovered in 1917 from a mine in Iron County, Michigan, United States and identified in 1930. As of 2012, seamanite is known from four sites in Michigan and South Australia.
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.
Titanowodginite is a mineral with the chemical formula MnTiTa2O8. Titanowodginite has a Mohs hardness of 5.5 and a vitreous luster. It is an iridescent dark brown to black crystal that commonly forms in a matrix of smoky quartz or white beryl in a complex zoned pegmatite.
Beraunite is an iron phosphate mineral. It was first described by August Breithaupt for an occurrence in Beraun currently in the Czech Republic. Beraunite occurs as a secondary mineral in iron ore deposits, and as an alteration product of primary phosphate minerals in granite pegmatites.
Cyrilovite (NaFe33+(PO4)2(OH)4·2(H2O)) is a hydrous sodium iron phosphate mineral. It is isomorphous and isostructural with wardite, the sodium aluminium counterpart.
Hureaulite is a manganese phosphate with the formula Mn2+5(PO3OH)2(PO4)2·4H2O. It was discovered in 1825 and named in 1826 for the type locality, Les Hureaux, Saint-Sylvestre, Haute-Vienne, Limousin, France. It is sometimes written as huréaulite, but the IMA does not recommend this for English language text.
Dzhalindite is a rare indium hydroxide mineral discovered in Siberia. Its chemical formula is In(OH)3.
Nabalamprophyllite has a general formula of Ba(Na,Ba){Na3Ti[Ti2O2Si4O14](OH,F)2}. The name is given for its composition and relation to other lamprophyllite-group minerals. Lamprophyllite is a rare Ti-bearing silicate mineral usually found in intrusive igneous rocks.
Kamiokite is an iron-molybdenum oxide mineral with the chemical formula Fe2Mo3O8. The name kamiokite is derived from the locality, the Kamioka mine in Gifu Prefecture, Japan, where this mineral was first discovered in 1975.
Kröhnkite ( Na2Cu(SO4)2•2H2O ) is a rare copper sulfate mineral named after B. Kröhnke who first researched it. Kröhnkite may be replaced by Saranchinaite, the anhydrous form of the mineral, if heated to temperatures above 200 °C (392 °F).
Simpsonite has a general formula of Al4(Ta,Nb)3O13(OH). It occurs as euhedral to subhedral tabular to short and prismatic crystals, commonly in subparallel groups. Under the petrographic microscope it has a very high relief.
Bobfergusonite is a mineral with formula Na2Mn5FeAl(PO4)6. The mineral varies in color from green-brown to red-brown. It was discovered in 1986 in Manitoba, Canada, and named for Robert Bury Ferguson (born 1920). As of 2012, the mineral has only been found in Canada and Argentina.
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.
Ferronigerite-2N1S is an iron, tin, alumino-hydroxide mineral that naturally occurs around sillimanite-quartz veins. Ferronigerite-2N1S belongs to the nigerite group, högbomite supergroup. The other constituents of the nigerite group are ferronigerite-6N6S, magnesionigerite-2N1S, magnesionigerite-6N6S, zinconigerite-2N1S and zinconigerite-6N6S. The 2N1S ending stands for the nolanite and spinel structural layers.
Billwiseite is a very rare oxide mineral found at the pegmatite commonly referred to as "Stak Nala" located within a few hundred yards from the village of Toghla in the Stak Nala, Gilgit-Baltistan Pakistan. It has only been found as a coating on a single crystal of lepidolite. The sole rock containing Billwiseite is kept at the Royal Ontario Museum, catalogue number M5595.
Béhierite is a very rare mineral, a natural tantalum borate of the formula (Ta,Nb)BO4. Béhierite is also one of the most simple tantalum minerals. It contains simple tetrahedral borate anions, instead of more common among minerals, planar BO3 groups. It forms a solid solution with its niobium-analogue, schiavinatoite. Both have zircon-type structure (tetragonal, space group I41/amd) and are found in pegmatites. Béhierite and holtite are minerals with essential tantalum and boron.
