CLINOCLASE (alternative names Clinoclasite and Abichite )

Clinoclase is a hydrous copper arsenate mineral with the chemical formula Cu3AsO4(OH)3. This rare secondary copper mineral typically forms acicular crystals within the weathered zones above copper sulfide deposits. It is characterized by its vitreous, translucent crystals that exhibit a dark blue to dark greenish-blue hue, as well as botryoidal masses. Clinoclase belongs to the monoclinic crystal system (2/m), has a hardness ranging from 2.5 to 3, and a relative density of 4.3. It is often found in association with minerals such as malachite, olivenite, quartz, limonite, adamite, azurite, and brochantite.

First identified in 1830 in Cornwall, England, clinoclase has also been located at Broken Hill in New South Wales, Australia, and is associated with copper ore deposits across several U.S. states, including Arizona, California, Montana, New Mexico, Nevada, and Utah. Additionally, it has been discovered in various countries, including France, Germany, the Czech Republic, Austria, Romania, Russia, and the Democratic Republic of the Congo. Clinoclase is also known by the alternative name abichite, with its type locality being the Wheal Gorland mine in St Day, Cornwall, United Kingdom.