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 Crete, "Malachite" sighted a British cruiser escorted by a destroyer. She launched two torpedoes at the target, but they both missed her by the stern. From 3 to 14 July 1941 she patrolled north of Ras Azzaz. At 20:00 on July 3 "Malachite" sighted a large cruiser (possibly ) escorted by two destroyers, and immediately launched a torpedo. There was an explosion heard, but there is no reports of this attack in British post-war documents, although some believe an escort was hit. From September 25 to October 5 1941 she patrolled off Ras Aamer. From January 20 to 27, 1942