MALICHITE.
Malachite is a green opaque mineral whose color indicates a salt of copper. It is a carbonate of copper containing water, the percentages being in the typical mineral, cupric oxide 71.9, carbon dioxide 19.9, and water 8.2. It is the common form which copper assumes when it or even its ores oxidize in the air. Many of the green stains on rocks or minerals can be correctly referred to malachite. It is only valued for ornamental purposes however when it occurs in compact masses usually exhibiting concentric layers. Malachite in this form takes a fine polish. Malachite is not a hard mineral, its hardness being between 3.5 and 4. It can therefore be scratched with a knife. It is comparatively heavy, weighing four times as much as an equal bulk of water. When heated before the blowpipe it fuses easily, coloring the flame green. By heating long enough on charcoal it can be made to yield a globule of copper. It is easily attacked by common acids, causing effervescence of carbon dioxide. This test can be used to distinguish it from the silicate of copper, chryscolla, which has the same color.
Besides its occurrence in massive forms as noted above Malachite not uncommonly occurs in tufts and rosettes incrusting other minerals. This is an especially common occurrence in mines in Arizona and affords specimens of great beauty especially when the green tufts of malachite are seen upon brown limonite, for then the appearance of moss on wood is closely simulated. Such material is of course too fragile to be used for decorative purposes.
Malachite is prepared for ornamental use by sawing masses of the character of those previously referred to into thin strips which are then fastened as a veneer on vessels of copper, slate or other stone previously turned to the desired shape. Putting pieces together so that neither by their outlines nor color will it appear that they are patchwork requires a high degree of skill and such work is done almost exclusively in Russia. Table tops, vases and various other vessels are manufactured in this way and form objects of great beauty. The pillars of the Church of Isaac in St. Petersburg are of malachite prepared in this way and there are similar pillars in the Church of St. Sophia, Constantinople, said to have been taken from the Temple of Diana at Ephesus.
Occasionally the desired object can be turned from a single piece of malachite, but pieces of sufficient size for this purpose are rare. Bauer describes one piece found in the Gumeschewsk mines which was 17½ feet long, 8 feet broad and 3½ feet high and compact throughout. This is probably the largest single mass known.
Russia furnishes most of the malachite suitable for work of this kind and the art of cutting and fitting the stone is possessed almost exclusively in that country. Most of the Russian malachite has been obtained from the mines of Nischne-Tagilsk and Bogoslowsk in the northern Urals, or Gumeschewsk in the southern. The supply has gradually decreased till now only the Nischne-Tagilsk mines are productive. The malachite is said to occur there in veins in limestone.
Besides the Urals, fine malachite suitable for cutting comes from Australia. Burra Burra in New South Wales and Peak Downs in Queensland are localities whence good Australian malachite is obtained.
Malachite as a mineral is common in copper mines in the United States but it is only in Arizona that it is found of a quality suitable for cutting. A variety from Morenci, Arizona, consists of malachite and azurite and gives a combination of green and blue that is unique and pleasing. (See colored plate.) Less use has been made of such material for ornamental purposes than might have been for most of it has unfortunately been smelted as a copper ore.
Malachite is rarely used for rings or small jewels but is cut into earrings, bracelets, inkstands and similar objects. Art objects of malachite seem to have been in much favor with Russian emperors as gifts to contemporaneous sovereigns, and so bestowed are to be seen in numerous palaces in Europe. Perhaps the most famous of these gifts is the set of center tables, mantel pieces, ewers, basins and vases presented by the Emperor Alexander to Napoleon and still to be seen in an apartment of the Grand Trianon at Versailles.
Malachite was well known to the ancients and like other precious stones was worn as an amulet. It was called pseudo-emerald by Theophrastus. Its name is from the Greek malake, the word for mallows and was given doubtless on account of its green color.