Crookesite
Selenide of copper, thallium and silver
(repeating unit)7(Tl, Ag)Se
4
H-M symbol: (4)
Crookesite is a selenide mineral composed of copper and selenium with variable thallium and silver.
Characteristics
Its chemical formula is reported either as Cu
7(Tl, Ag)Se
4 or (Cu, Tl, Ag)
2Se.[4] It is formed by precipitation from hydrothermal fluids, and contains by mass: 16.3% Tl, 47.3% Cu, 2.9% Ag, and 33.6% Se.[2]
Crookesite is an opaque, bluish grey to pink toned brown metallic mineral crystallizing in the tetragonal system. It has a Mohs hardness of 2.5 to 3 and a specific gravity of 6.9.
Name and discovery
It was discovered in 1866 in Skrikerum, Sweden and named for Sir William Crookes (1832–1919), the discoverer of the element thallium.[2]
See also
- List of minerals
- List of minerals named after people
- Sabatierite – Selenide of copper and thallium
References
- Berger, Rolf A.; Sobott, Robert J. (1987). "Characterization of TlCu7S4, a crookesite analogue". Monatshefte für Chemie. 118 (8–9): 967–972. doi:10.1007/BF00815324. S2CID 102058943.
- Berger, R..A. (1987). "Crookesite and sabatierite in a new light. A crystallographer's comment" (PDF). Zeitschrift für Kristallographie. 181 (1–4): 241–249. Bibcode:1987ZK....181..241B. doi:10.1524/zkri.1987.181.1-4.241.
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