Crookesite
Selenide of copper, thallium and silver
01Characteristics
Its chemical formula is reported either as Cu
7(Tl, Ag)Se
4 or (Cu, Tl, Ag)
2Se. 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.
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.
02Name and discovery
It was discovered in 1866 in Skrikerum, Sweden and named for Sir William Crookes (1832-1919), the discoverer of the element thallium.
Sources and credits
This article is adapted from the Wikipedia article “Crookesite”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- Crookesite.jpg by David Hospital, CC BY-SA 4.0
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