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PRECIOUS STONES.
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This precious stone is one of the very few containing fluorine,
Dieulafait says the only one, but some other writers give this element as one of the constituents of tourmaline. The crystals assume the geometrical form of prisms with
only one end terminating regularly, and exhibit distinct pleochroism, double refraction, and strong electric powers. The topaz holds the rank of eight in the scale of hardness, and exhibits greatly diversified colors, including different shades of yellow, gray, blue, rose, pink, red, green, citron, and a white, or colorless variety; the last often passes for diamond on account of its great brilliancy, as in the enormous Braganza or Portuguese gem generally supposed to be a topaz. The " Minas Novas," a white Brazilian topaz, so called from the province where it is found, is sometimes sold for diamond. This species of precious stone is found in India, Siberia,
Australia, Saxony, Austria, Brazil, Mexico, and in Maine, Connecticut, North Carolina, New Mexico, Colorado, and Arizona, in the United States. The Colorado specimens — one having been discovered weighing more than thirty carats,— are of a beautiful light blue color ; the yield at Pike's Peak, as stated in Leslie's Magazine, exceeded at the time of writing one hundred dollars per annum. Though found in large crystals, only a small portion of these specimens are suitable for jewelry. Beautiful varieties occur in Siberia, saffron-yellow in India, wine-colored and pale violet in Saxony, a sea-green sometimes called aquamarine, in Bohemia, and blue in Scotland, while Brazil furnishes specimens in gold, ruby, rose, sapphire-blue, and light blue colors. The fine, delicate, sherrycolored stones from Siberia soon fade in the light, and on this account such specimens in the British Museum are kept covered. The gem known as Brazilian sapphire is blue topaz, and
Brazilian ruby is either red tourmaline or yellow topaz, changed |
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