ADAMANTINE SPAR, a simple mineral, more commonly deno minated Corundum by mineralogists, the name given to it in India, from which country it was first brought to Europe. first specimens of it were sent by Dr. Anderson, of Madras, to Mr. Berry, a lapidary in Edinburgh, as the substance used in India to polish masses of crystal and all other precious stones, except the diamond. It was examined by Dr. Black, who ascertained its peculiar nature, and from its great hardness he called it Adamantine Spar. With the exception of the diamond, it is the hardest substance known. It contains about 90 per cent. of alumine, a little iron, and Et little silica, is usually of a pale grey or greenish colour, but is also found of various tints of red and brown. It is usually met with in rough ill-defined Crystals, in granite, and sometimes in primary limestone, and is found in China, many parts of India, and occa sionally in different parts of Europe. Emery, the well-known substance used in the cutting and polishing of glass, in polishing steel, making razor-straps, and similar purposes in the arts, is a granular variety of Coruudum, usually very much mixed with iron ore. It is chiefly imported from the Isle of Naxos, in the Grecian Archipelago, but is also found in Saxony. The Sapphire is a
remarkable instance how the mysterious chemistry of nature in the mineral kingdom produces from the same eletnents substances the most different in external form; this beautiful precious stone yielded by the analysis of Chenevix 94 per cent. of alumina; and Tennant found in emery, when freed from its admixture of iron, 92 per cent. of the same earth. The sapphire is, after the diamond, the most valuable of gems; it is usually dark blue, but also occasionally colour less, and the precious stones called by lapidaries Oriental Ruby, Oriental Topaz, Oriental Amethyst, and Oriental Emerald, are red, yellow, violet, and own Sapphires, distinguishable from the other gems of the same name which have not the prefix Oriental, by their greatly superior hardness and greater specific gravity. Sapphires are found in gravel and sand in the island of Ceylon and in Pegu, but they have never been seen in a matrix. They are also occasionally found in gravel in different parts of Europe, and they have been met with of a clear blue colour and crystallised, in the lava of Nieder Mendig, near Andernach on the Rhine.