Stone of the Week - Malachite

Malachite is considered a carbonate of copper, and is often seen with Azurite (another copper carbonate). Malachite commonly forms by the oxidation of copper – hence it is often found near copper deposits. It can also form when deposited by metoric water in sandstones. The word malachite comes from the Greek word molochitis, meaning "mallow-green stone", presumably due to the fact that it is not a hard mineral and thus easily worked with.

Malachite can occur as acicular crystals (left), as its common botryoidal form (center), and often found with azurite (right).

Malachite has a brilliant green color, of varying shades, but occurs only as green – no other color. Usually it is seen as alternating bands of light and green, in what are called botryoidal masses. Botryoidal means that it forms in spherical aggregations, giving it a bumpy or nodular look. Malachite can occur in a variety of other forms, including fibrous, stalagmitic, or even as acicular crystals (pointed or needle like); it can also be found in large masses with no distinct form.

Malachite is available in many styles for jewelry work.

Malachite was often worn by the Greeks and Romans as a form of protection against evil spirits. Malachite was also once used as a pigment for green paint until replaced with a synthetic version. It is more often valued for its decorative appeal, and was very popular with the Russian Czars and was used to form the columns St. Issacs in Leningrad. Tsar Nicholas II gifted "The Tazza" to August Heckscher in 1910, later given to the Linda Hall Library located in Missouri. Today it is a popular gemstone to use in jewelry, as it is ‘soft’ enough to cut, but not so fragile that it would be difficult to use in jewelry work.

The Tazza at the Linda Hall Library reading room, Missouri

Care and Cleaning: While it is not recommended to soak malachite in water for extended periods, a soft damp cloth should be sufficient to clean up any of your pieces. It is also not recommended to expose it to heat nor acids.

If you have a stone you would like to know about, please feel free to leave a request in the comments section. Have a mystery stone? Leave a link in the comments to a picture of it, and it may be featured as a part of this series!


Malachite Facts:
Chemical composition: Cu2CO3(OH)2
Color: Green
Habit: Commonly botryoidal, also massive, stalagmitic, fibrous, or acicular crystals
Fracture: Uneven or subconchoidal
Cleavage: Good
Luster: Vitreous/dull to silky
Hardness: 3.5-4
Specific Gravity: 3.9-4
Streak: Green
Occurrence: Worldwide; large quantities in the Ural Mountains


References
A Guide to Rocks and Fossils by B. Busbey III, R. R. Coenraads, P. Willis, and D. Roots. Published 2002 by Fog City Press. ISBN: 1877019518

Rocks, Minerals, & Fossils of the World by C. Pellant and R. Phillips. Published 1990 by Little, Brown and Co. ISBN: 0316697966

Wikipedia – Malachite. http://en.wikipedia.org/wiki/Malachite

Wikipedia – Tazza. http://en.wikipedia.org/wiki/Tazza