Physico-chemical foundations of malachite synthesis and structural-morphological peculiarities and properties of its man-made jewelry quality varieties

Abstract

Malachite, the basic copper carbonate, is a typical mineral of oxidation zone of sulphide copper deposits. Because of its bright green color, intricate patterned texture, chatoyancy, as well as a wonderful polishing, since long it has been used in jewelry stone-cutting. In this respect the famous Ural malachite is especially popular. However, its deposits are practically exhausted. Though there are rich reserves of malachite in African deposits, still they are not of such high jewelry qualities as that from the Urals. Besides stone-cutting and jewelry trade, malachite is also used for making catalizers, corrosion-resisting coating, pigments and different pesticides (8,12). For these purposes natural malachite, as well as its synthetic analogue, produced under industrial conditions as a finely ground powder, has been already used for many years. As far as synthetic man-made jewelry quality malachite is concerned, the problem of its synthesis was solved about IO years ago in the USSR, where the synthesis was accomplished first in the Leningrad State University (16), followed by the All-Union Institute for the Synthesis of Mineral Raw Materials (VNIISIMS) Ministry of Geology of the USSR (6), and the Institute of Experimental Mineralogy (IEY) USSR Academy of Sciences (I). These institutions devised original methods which allow nearly all textural varieties found in natural malachite to be synthesized under chosen conditions.