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 December 1942 she patrolled an area between the island of La Galite and Cape de Fer. She patrolled off the island of La Galite on January 4 and 5 1943 again. On January 21 "Malachite" was deployed to an area between Cape Carbon and Cape Bougaroun. At 4:55 on January 22 she sighted an incoming convoy heading to Bona. At 05:18 she fired four torpedoes, and dove to avoid an attack by the escorts. Two explosions were heard, but again British post-war documents contain no mention of this attack. On February 2, 1943 "Malachite" left Cagliari with a group of