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
The Malachite Box Furthermore, Pavel Bazhov indicated that his stories can be divided into two groups based on tone: "child-toned" (e.g. "The Fire-Fairy", "Silver Hoof"), and "adult-toned" ("The Stone Flower", "Marko's Hill"). Denis Zherdev divided the stories into "gold" and "malachite" series, which begin with "Beloved Name" and "The Mistress of the Copper Mountain" respectively. In the mid-1930s Sverdlovsk Publishing House decided to publish the collection "Prerevolutionary Folklore of the Urals" (). In the summer of 1934 the folklorist Vladimir Biryukov was offered to make such a collection. The historian Andrey Ladeyshchikov became its chief editor. From August to December 1935 Biryukov collected