Malachite is an opaque green stone which, when cut, shows layers of lighter and darker concentric rings, parallel lines or other shapes caused by its shell like formation. Although it is not very hard and resistant, Malachite is popular for jewellery and ornaments. Care should be taken to avoid chemicals, acids and solvents when cleaning – washing in cool soapy water and leaving to dry naturally is the best method for cleaning malachite. Zaire is the most important producer of malachite. It is not an expensive stone.