Chrysocolla

minerals

malachite

azurite

cuprite

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Formula: (Cu2-xAlx)H2-xSi2O5 (OH)4.nH2O phyllosilicate (sheet silicate)
Specific gravity: 2.0 to 2.2
Hardness: 2 to 4
Streak: Greenish white
Colour: Light blue, blue, greenish blue
Solubility: Slightly soluble in hydrochloric, sulphuric and nitric acid. Insoluble in water.
Environments:

Hydrothermal environments

Chrysocolla is a secondary mineral that forms in the oxidation zone of all types of hydrothermal deposits, often encrusting or replacing earlier secondary minerals. It is associated with malachite, azurite, cuprite and native copper.

Localities

At the Whim Creek copper mine, Roebourne Shire, Western Australia, a chrysocolla pseudomorph after malachite after azurite has been found with wulfenite. This is a double pseudomorph showing a change of chemistry twice over to end up with a complete chrysocolla replacement of the original azurite, with malachite as a transitional stage (KL p244).

At Westernhope Old Mine, Stanhope, County Durham, England, UK, coatings of chrysocolla on quartz-ankerite matrix have been found on the spoil heaps (JRS 7(1).9).

At Higher Roughton Gill, Caldbeck, Allerdale, Cumbria, England, UK, chrysocolla is common at the vein exposures as botryoidal crusts with pyromorphite, hemimorphite or hydrocerussite and as thick blue to green vein infillings, coloured by included malachite. Chrysocolla commonly replaces and encrusts malachite (JRS 11.11).

At Red Gill Mine, Roughton Gill, Caldbeck, Allerdale, Cumbria, England, UK, pseudomorphs of chrysocolla after malachite and after linarite have been observed (JRS 11.35).

At the 79 mine, Pinal county, Arizona, USA, pseudomorphs of chrysocolla after hemimorphite have been found (R&M 94.2.169).

At the Bagdad mine, Yavapai county, Arizona, USA, massive chrysocolla is common, and rare large pseudomorphs of chrysocolla after azurite have been found in the oxide zone, also equally rare chrysocolla after malachite after azurite (R&M 94.2.164).

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