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Chrysoprase,
Other names given to this beautiful apple-green stone are Swiss Jade or New Jade.
The jades are imitated by a number of other natural minerals including serpentine, aventurine and chrysoprase.
However chrysoprase is a crypto-crystalline type, of the Quartz family, composed of a mass of minute crystalline fibres. Chalcedony is the general term used for this type of quartz, variety names being given to the different colours, e.g. "cornelian"-a translucent flesh red; "chrysoprase" - a translucent apple green.
This apple green variety of chalcedony, coloured by nickel oxide, comes by the name of chrysoprase from the Greek word meaning golden-green. In ancient times it was very highly esteemed. The period of greatest use was the Classical era and the 19th century.
Chrysoprase is one of only a handful of stones that result from the weathering processes of the sedementary cycle of rock and mineral formation.The others being turquoise, malachite and azurite. Weathered rock, exposed to water and wind, can accumulate dry deposits which in turn become compressed. "Deposits are found in Australia, Poland (Silesia), India, USA and Canada."
According to the Mohe Scale of hardness (1-10) chrysoprase rates a 7, similar to amethyst. By comparison, amber measures 2 to 2.5, opal is 5 to 6.5, and diamond is 10.
The National Association of Goldsmiths of Great Britain recommend Chrysoprase as an alternative birthstone for the month of May, instead of what can be the more costly emerald.
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