Distinctive features The characteristic colors arranged in zones and the mid-level hardness and exceptional luster of the stones generally make identification of chalcedony quite easy. It is worth remembering, however, that it has a slightly lower density and hardness than other quartzes. Occurrence Large amounts of chalcedony come from Uruguay and the bordering regions of Brazil, but it is found in many other countries.
Chrysoprase comes mainly from Germany, the Soviet Union, the United States, Canada, and Brazil.
Value Its value was quite high in antiquity, when chalcedony was one of the main gems used. Nowadays, it is fairly low, except for chrysoprase, attractively colored speciniens of which are quite valuable. Objects in chalcedony of considerable artistic merit tend to fetch high prices. In the past chalcedony was imitated by glass, moulded pieces even being used to simulate carved stones, It is not produced synthetically. Because chalcedony is porous, it has long been the practice to impregnate it with artificial dyestuffs, making it look like onyx, even where the original color is almost uniform.