(b) Holotype material of tennantite-(Cu), associated with the same phases shown in (a), as seen in reflected light microscopy (partly crossed polars). Catalogue number P1P 74/2020. The image is published in an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ( https://creativecommons.org/licenses/by/4.0/ ). — Photo: Cristian Biagioni, Jiří Sejkora, Yves Moëlo, Eric Marcoux, Daniela Mauro and Zdeněk Dolníček · CC BY-SA 4.0
Tennantite-(Cu)
Tennantite-(Cu) is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Cu₆(Cu₄Cu₂)As₄S₁₃.
It crystallizes in the cubic crystal system (space group I-43m). It is a member of the Tetrahedrite structural group.
Key properties: Mohs hardness 3.5–4; specific gravity 4.656; Black streak; Metallic luster.
IMA symbol Tnt-Cu, IMA status: approved, named in 2021.
Found in an epithermal hydrothermal vein deposit by replacement of enargite under decreasing fS2.
It is found associated with Enargite, chalcopyrite, vinciennite, pyrite.
The mineral was named to honor the English chemist Smithson Tennant (1761-1815) with a suffix for the dominant divalent cation in the C site.