chrysocolla specimen of this hydrated copper phyllosilicate mineral
Its name in Greek means golden lime and was mentioned as a known mineral by the ancient Greek philosopher, surgeon and natural scientistTheophrastos (372-287 BC). At that time it was used as an ornamental stone. Strangely enough, it was not mineralogically described until 1968. Chrysocolla usually occurs in thin coverings or encrustations, which resemble malachite in colour. It is distinguishable from malachite by theblue shadow. Chrysocolla originates as a secondary product of the disintegration of chalcopyrite and other sulphide compounds of copper. Limonite and opal often make it impure, or it is permeated by malachite. These were the very admixtures which made the exact identification of chrysocolla’s chemical composition so extremely difficult.Chrysocolla is not a particularly import ant copper ore. As a precious stone it is used only rarely (in Israel and Russia).Chrysocolla forms in the altered parts of copper deposits. It occurs with azurite, Malachite and cuprite. It is also an important mineral for ore prospectors, as its presence may suggest that copper deposits are nearby.Composition is very variable from the presence of impurities, but it is considered essentially a hydrous silicate of copper CuSiO3.2H20. It is sometimes considered to contain a variable amount of free silica, and some specimens are sufficiently hard to scratch glass and to be cut and polished for jewellery.
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