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 a range of at . The boats were armed with six internal torpedo tubes, four in the bow and two in the stern. One reload torpedo was carried for each tube, for a total of twelve. They were also armed with one deck gun for combat on the surface. The light anti-aircraft armament consisted of one or two pairs of machine guns. "Malachite" was built by OTO at their shipyard in Muggiano, laid on 31 August 1935, launched on 15 July 1936 and complaeted on 6 November 1936. After delivery, "Malachite" was assigned to the 13th Squadron based at La