Sunday, April 19, 2009

Malachite and Rhodochrosite

Malachite

Malachite is another carbonate mineral, like rhodochrosite; specifically, it is copper carbonate.

It is often formed by when copper ores, found around limestones, are weathered. It often forms stalacmites.

Like many copper compounds, it is green. As a result, it was used as an artist's pigment until around 1800.

It has been mined for over 3,000 years at the so-called "King Solomon's Mines" in Israel.

Rhodochrosite

Rhodochrosite is made of crystals of magnesium carbonate. The pure form is rose red, but this is rare. Impure varieties are pink or brown.

This specimen is from a stalactite, of a kind found uniquely in an old Inca silver mine in Catamarca, Argentina.

It has been cut in cross-section, revealing concentric bands of light and dark rose-coloured layers.

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