|Clinoclase Crystals. Photo Copyright © Elmar Lackner|
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. The crystal system is monoclinic 2/m. It 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 : Cu3(AsO4)(OH)3
Crystal System: Monoclinic
Color: Dark greenish blue to greenish black; in transmitted light, blue-green.
Hardness: 2.5 - 3.0
Occurrence: A rare secondary mineral in the oxidized zone of some arsenic-rich hydrothermal
Association: Olivenite, cornwallite, cornubite, conichalcite.
The type locality for clinoclase is the Wheal Gorland mine at St Day, Cornwall in the United Kingdom.
Clinoclase was discovered in 1830 in the county of Cornwall in England.
Abichite is another name for clinoclase.
The specimen in the photo is From: Tin stope, Majuba Hill Mine (Majuba Mine; Mylar Mine; Tin Mine; Nevada Bureau of Mines and Geology sample sites 2844 & 2846), Antelope District, Pershing Co., Nevada, USA