TIEMANNITE
TIEMANNITE Tiemannite – HgSe – is a very rare selenide, characteristic of hydrothermal veins and occurring with other Se minerals. It can be part of Se ores, but Se is usually obtained as a by-product in the refining of Cu, Ni, and Pb ores. It is classified in the Sphalerite Group, forming a series with […]
TRIPLITE
TRIPLITE Triplite -(MnFe)2PO4(F,OH) – is a rare phosphate, characteristic of phosphorus-rich granitic pegmatites. It is not an ore. It is classified in the Triplite Group, in the Triplite-Zwieselite Series. It is the Mn analog of zwieselite and may contain Sc as an impurity. There are two varieties (altered triplite and a variety with Mg). Macroscopically, […]
THORIANITE
THORIANITE Thorianite – ThO2 – is a rare oxide, of no importance as an ore. It is classified in the Uraninite Group, in the Thorianite-Uraninite Series. Impurities may include Pb, U, Ce, Nd, Pr, La, Zr, and He. The Pb present is probably radiogenic. There are four varieties (with up to 12.5% Pb, with up […]
TAENITE
TAENITE Taenite – (Fe,Ni) – is a native iron-nickel element that occurs in meteorites and in some very specific terrestrial geological situations. It is classified in the Iron Group. It can contain Cu, Co, P, S, and C and is strongly magnetic. 1. Characteristics Crystal system: Cubic hexaoctahedral. Color: Grayish white, silvery […]
THOMSONITE
THOMSONITE Thomsonite – NaCa2[Al5Si5O20].6H2O – is a tectosilicate from the Zeolite Group. It typically occurs as a secondary mineral in vesicles and fractures of volcanic rocks and is not common; it is one of the rarest zeolites. It has no economic importance. “Thomsonite” is currently no longer considered a mineral, but a generic term that […]
TAPIOLITE
TAPIOLITE Tapiolite – (Fe,Mn)(Ta,Nb)2O6 – is a very rare oxide, characteristic of some granitic pegmatites. It is not considered an ore due to its rarity. The term “tapiolite” is used for unanalyzed minerals of the Tapiolite-(Fe) – Tapiolite-(Mn) Series. Tapiolite has the same composition as columbite and tantalite, but is tetragonal instead of orthorhombic. Tapiolite-(Fe) […]
TETRADYMITE
TETRADYMITE Tetradymite – Bi2Te2S – is a rarer sulfide, characteristic of Bi deposits. It is never the main ore mineral in the deposit, but it is common, always in small quantities. Apparently, tetradymite is more stable when enriched in S, with the formula Bi14Te13S8, compared to stoichiometric tetradymite. Tetradymite is classified in the Tetradymite Group, […]
TENORITE
TENORITE Tenorite – CuO – is a fairly common oxide, used for centuries as a copper ore (~80% Cu). It is a mineral without distinct and/or diagnostic macroscopic characteristics, as it is black, usually massive to earthy, and typically has a high impurity content. Crystals are very rare, reaching a maximum of 2 mm, and […]
TODOROKITE
TODOROKITE Todorokite – (Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12·3-4H2O – is a relatively common oxide found in Mn ores. The crystals appear as very small fibers, up to 0.05 mm, forming bands with the fibers arranged perpendicularly to the band surface. The fibers can be compact or isolated; they can group together in very porous aggregates, form earthy aggregates, and […]
TANTALITE
TANTALITE Tantalite is a rare oxide, yet it constitutes the primary ore of tantalum (Ta). “Tantalite” is currently an obsolete name that was applied to minerals now classified within the Tantalite-(Fe)–Tantalite-(Mn) series. The Mn-rich members are generally more abundant. Tantalite and columbite share the same structure and similar chemistry, resulting in similar properties. Within the […]