Clinoclase Crystals

Clinoclase is a rare secondary copper mineral and forms acicular crystals in the fractured weathered zone above copper sulfide deposits. It occurs in vitreous, translucent dark blue to dark greenish blue colored crystals and botryoidal masses. Clinoclase crystal system is monoclinic 2/m. Clinoclase has a hardness of 2.5 - 3 and a relative density of 4.3. Associated minerals include malachite, olivenite, quartz, limonite, adamite, azurite, and brochantite among others.

Clinoclase was discovered in 1830 in the county of Cornwall in England.  

Abichite is another name for clinoclase. 

Clinoclase Crystals
Clinoclase Crystals. Tin stope, Majuba Hill Mine, Antelope District, Pershing Co., Nevada, USA
Photo Copyright © Elmar Lackner

Clinoclase : Cu3(AsO4)(OH)3
Crystal System: Monoclinic
Color: Dark greenish blue to greenish black; in transmitted light, blue-green.
Hardness: 2.5 - 3.0
Tenacity: brittle
Occurrence: A rare secondary mineral in the oxidized zone of some arsenic-rich hydrothermal
base-metal deposits.
Association: Olivenite, cornwallite, cornubite, conichalcite.
The type locality for clinoclase is the Wheal Gorland mine at St Day, Cornwall in the United Kingdom.

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