Chrysocolla quartzite malachite primary Ref490

Chrysocolla partially covered with quartzite and primary malachite.

Dimensions : 41mm x 31mm x H : 45mm.

Weight with base: 64g.

 Chemical composition

Cu₂H₂Si₂O₅(OH)₄ - nH₂O

This is a hydrated copper silicate.

Its formula may vary slightly depending on its degree of hydration.

Density

Approx. 2.0 to 2.4 (low density, mainly due to its water content).

Hardness (Mohs scale)

Between 2.0 and 4.0, depending on the degree of silicification.

Pure chrysocolla: soft and brittle (2 to 2.5)

Silicified chrysocolla (often called "gem chrysocolla"): up to 6-7.

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With advances in mineralogy in the 19th century, chrysocolla became a good indicator of the presence of copper. It forms in the oxidized zones of copper deposits, often in association with malachite, azurite or cuprite. Although it contains copper, it is not widely mined as an ore, as its content is generally too low.

Today, chrysocolla is appreciated mainly for its aesthetic value. When partially silicified - i.e. hardened with quartz - it gains in strength and can be polished.