Mineralpedia Details for Clinoclase

Named after the Greek words for “incline,” klino, and “fraction,” klasma, in reference to the inclined cleavage planes. Clinclase is an uncommon mineral that occurs in small amounts in oxidized arsenic-rich hydrothermal base metal deposits. Localities for Clinoclase include in England, France, Germany, Italy, Slovakia, the United States, Argentina, Chile, South Africa, Japan, and Australia, among several other minor localities. Associated minerals include olivenite, cornwallite, cornubite, and conichalcite.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/clinoclase.pdf

Formula

Cu₃AsO₄(OH)₃ 

Crystal System

Monoclinic 

Crystal Habit

Crystals rare, typically needlelike, tabular, as rosettes and radial fibrous spherical aggregates, as crusts and coatings. 

Cleavage

perfect 

Luster

Vitreous, pearly on cleavages 

Color

Dark greenish blue to greenish black; in transmitted light, blue-green. 

Streak

Bluish green 

Geological Setting

A rare secondary mineral in the oxidized zone of some arsenic-rich hydrothermal base-metal deposits. 

Class

2/m - Prismatic 

Fracture

Uneven 

Hardness

2.5 - 3 

WebMineral

View Clinoclase 

Mindat

View Clinoclase 

Light to dark blue prismatic crystals to 3mm.

Elongated, dark blue bladed crystals to 1mm.

Platy blue Clinoclase crystals in radial patterns to 3mm across.

Clinoclase crystals as translucent blue bladed singles to 0.5mm and composite dark blue, curved, sheaf-like bundles to 1mm on Cornubite and/or Cornwallite.

Deep blue, lustrous, tabular, well-defined crystals of Clinoclase to 2mm overgrown on brighter green botryoidal Cornwallite.

Deep blue, lustrous, thick tabular crystals of Clinoclase to 1mm with good coverage over a bed of botyroidal dark green Cornwallite and/or Cornubite.

Deep glassy blue tiny prismatic crystals to 1mm.

Deep blue crystal groups to 5mm in several areas on Cornwallite, the beady green. Minor Olivenite as seen in photo. A good specimen for this mine, which is seldom on the market. Wheal Gorland is the mine in which all the fantastic Liroconite was discovered.

Rich deep blue Clinoclase with green Conichalcite.