50.0 MB (2.7 MB compressed)
4665 x 3746 pixels
39.6 x 31.8 cm ⏐ 15.6 x 12.5 in (300dpi)
DIRK WIERSMA / SCIENCE PHOTO LIBRARY DIRK WIERSMA / SCIENCE PHOTO LIBRARY
Malachite is a hydrated copper carbonate with chemical formula Cu2CO3(OH)2. It crystallizes in the monoclinic crystal system, and usually occurs in amorphous (non crystalline) form. Malachite is often formed by precipitation from hydrothermal fluids in open spaces (voids) of rocks containing or associated with copper ores. Such precipitation takes place layer by layer, much like stalactites, forming rounded bulbs that eventually lead to a botryoidal (grape-like) or kidney-shaped surface. When polished, the internal banding of the peel by peel precipitation becomes visible. Malachite is famous for its vivid green colours and is extensively worked into trinkets and all kind of small ornaments. This specimen is from the Congolese copper-mining province Shaba and measures about 20 cm across.
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