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There are certain stones and other minerals which, owing to their possession of numerous microscopically fine cavities, of a globular or tubular shape, have the appearance of “rays” or “stars,” and these are called “asteriated.” Several of such stones have been discussed already in the last chapter, and in addition to these star-like rays, [...] The Sapphire is not so easy to imitate, as its hardness exceeds that of the ruby, and imitations containing its known constituents, or of glass, are invariably softer than the natural stone. As before remarked, almost any form of corundum other than red is, broadly, called sapphire, but giving them their strictly correct designations, [...] This mineral is a species of crystal, or crystalline alumina -an almost pure anhydrous alumina, Al2O3 -in many varieties, both of shape and colour. The chief stone is the ruby, considered, when large, to be of even more importance and value than the diamond. There are many other red stones in this group; sapphires, [...] To recapitulate certain of the facts respecting the diamond. -This wonderful gem has the distinction amongst precious stones of being unique; though many are composed of two, three, or but a small number of elements, the diamond is the only stone known consisting of one element, and absolutely nothing else -pure crystallised carbon. [...] Black gemstones Hardness. Specific Gravity. Diamond 10 3.502-3.564 Garnet 6-1/2-7-1/2 3.400-4.500 Jet 3-1/2 1.348 Onyx (a variety of Chalcedony) 6-1/2 2.598-2.610 Quartz 7 2.670 Tourmaline (not unlike Black Resin in appearance) 7-1/4 3.024-3.300 Related PostsTourmaline as talisman Virtues of carbuncle Healing stones |
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