Klockmannite

klockmannite

umangite

clausthalite

eucairite

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Formula: Cu5.2Se6
Selenide
Crystal System: Hexagonal

Specific gravity: 5.99 measured, 6.12 calculated
Hardness: 2 to 2½
Streak: Grey to black
Colour: Grey-black to black, may tarnish to blue-black
Common impurities: Ag
Environments

Hydrothermal environments

Klockmannite is of hydrothermal origin, in deposits rich in copper and tellurium. Associated minerals include clausthalite, umangite, eucairite, berzelianite, crookesite, chalcomenite, azurite, chalcocite, cobaltomenite, covellite, crookesite, goethite, kru'taite, malachite, penroseite, pyrite and tellurite (HOM, Mindat).

Localities

At the type locality, the Las Asperezas mine, Sierra de Cacho, Villa Castelli, General Lamadrid department, La Rioja Province, Argentina, klockmannite is found as granular aggregates in calcite associated with umangite, clausthalite, eucairite, crookesite, chalcomenite and berzelianite, often strongly altered to malachite and chalcomenite (AM 14.41, Mindat).

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