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 both miss. "Malachite" was forced to dive and undergo lengthy depth charge attack. From 10 to 18 April 1941 she was posted northeast of the Gulf of Sollum. At 23:37 on April 14 "Malachite" sighted a large convoy but was prevented from attacking it due to preemptive action by the escorts. On May 20, 1941 "Malachite" together with numerous other submarines was deployed to an area between Crete, Alexandria and Sollum, to support the German invasion of Crete (Operation Merkur). "Malachite"'s area operation was south of the island of Gaidaro. On the night of June 19, 1941 while patrolling off