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THE BERYL. 179
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to pink by artificial heat ; Scotch or " false topaz," is simply
yellow quartz. Limpid pebbles consisting of genuine topaz are called gouttes a'eau. Mawe says the river-beds of Brazil yield white, blue, and sea-green varieties, and Burton found both the topaz and the ruby in the itacolumite of this country ; the former has been known to occur in granite, and possibly it may exist in other kinds of rocks. Topaz is seldom found in large crystals without defects,
but it sometimes constitutes massive rocks which, in Saxony, are called "topaz fels." Specimens of immense size in a crystalline form have been taken from the Urals ; one of this description in the collection of St. Petersburg, of a wine color and perfectly transparent, has been differently estimated to weigh twenty-two and one-half, and thirty-one pounds ; another, found in Scotland, has a weight of nineteen ounces. A topaz described by Tavernier, belonging to the Emperor Aurungzeeb, which was purchased at Goa for nearly sixty thousand dollars, weighed one hundred fifty-seven and three-fourths carats. Very fine specimens of this gem were exhibited at the London Exposition of 1851, from New South Wales and other regions ; the brilliant mineral sent from Russia as phenakite, when subjected to the test of specific gravity, proved to be topaz. It has been said that this precious stone has never been
engraved, but this is an error, on good authority, since several of this class are known to exist. An antique engraving bearing a star or a cluster of stars has been counted with the treasures of St. Petersburg ; another, engraved with the portraits of Philip II. and Don Carlos, is in the Royal Library of Paris ; and a third, inscribed with a motto in Arabic, is thought to be owned in the same city. As an ornamental stone, the topaz is less popular than formerly ; therefore, its commercial value is small compared with some other gems. |
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