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Formula: (Cu2-xAlx)H2-xSi2O5(OH)4.nH2O
Phyllosilicate (sheet silicate)
Crystal System: Orthorhombic
Specific gravity: 1.93 to 2.4 measured
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:
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 Mount Kelly deposit, Gunpowder District, Queensland, Australia, the copper ores
overlie primary zone mineralisation consisting of
quartz-dolomite-sulphide veins hosted
in siltstone and schist.
Chrysocolla is common throughout the oxide zone associated with
malachite, and also coating siderite;
late-stage chrysocolla has also been observed with chalcotrichite
fibres growing from it
(AJM 22.1.21).
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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