Mineral Examples of such minerals are malachite (green) and azurite (blue). In contrast, allochromatic elements in minerals are present in trace amounts as impurities. An example of such a mineral would be the ruby and sapphire varieties of the mineral corundum. The colours of pseudochromatic minerals are the result of interference of light waves. Examples include labradorite and bornite. In addition to simple body colour, minerals can have various other distinctive optical properties, such as play of colours, asterism, chatoyancy, iridescence, tarnish, and pleochroism. Several of these properties involve variability in colour. Play of colour, such as in opal, results in
Italian submarine Malachite in Cagliari, when already in view of the Sardinian coast she was spotted by the Dutch submarine HNLMS Dolfijn in the morning of February 9, 1943. At approximately 11:00, HNMS Dolfijn launched a salvo of 4 torpedoes at "Malachite". The Italian submarine managed to avoid three of them by deftly maneuvering, but the fourth one hit her on the stern, and she sank within a minute taking down 35 crew with her. Commander Cinti, three other officers, and nine NCOs and sailors managed to escape. The wreck of "Malachite" was located in September 1999 at a depth of 117 to