MALACHITE, an ore of copper, presenting in its finer varieties a beautiful green colour which has led to its use as an ornamental stone. It is chemically a hydrated basic carbonate of copper, and appears to have been formed in most cases by the action of meteoric agencies on native copper, red oxide of copper, copper pyrites, and other ores. Upon these minerals the malachite frequently forms an incrustation. Although occasionally found in crystals belonging to the monoclinic system, its usual mode of occurrence is in stalactiticand stalagmitic forms,—frequently with a globular, botryoidal, or mammillated surface; while in other cases it forms compact and even earthy masses. The stalagmitic varieties display, when fractured, a beautiful internal structure, being made up of concentric zones of light and dark tints; and it is upon this structure that much of the beauty of polished malachite depends. The colours include various shades of apple-green, emeraldgreen, and verdigris-green. Certain varieties of the mineral exhibit, when fractured, a finely fibrous texture and soft silky lustre. The name malachite is derived from μαλαχή (the mallow), in allusion to the resemblance of the colour of the mineral to that of mallow leaves. Malachite was probably one of the green minerals described by Theophrastus under the general name of σ∕χαpαγδos, or emerald. It is believed to have been the smaragdτιs medicus of Pliny, while the molochitis of that author does not appear to have represented our modern malachite. Malachite is a mineral of very wide geographical distribution, being found more or less abundantly in the upper part of most deposits of copper ore. The finer varieties, such as lend themselves to purposes of ornament, are, however, found only in »Siberia, ...