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The Topaz 125
Several
minerals are commonly called topaz; yellow sapphire is called "
Oriental topaz"; and varieties of quartz are called " Saxon," "Scotch,"
"Spanish," "Smoky," and "False" topaz. The hardness, weight, and power
of developing frictional electricity, possessed by the true topaz,
enable investigators to distinguish real topaz from these nominal
varieties.
Topaz
commonly occurs in gneiss or granite, associated with tourmaline, mica,
or beryl, and occasionally with apatite, fluor-spar, and tin. The
purest variety of topaz, perfectly colourless and pellucid, is not
uncommon; as crystals it is found in Miask, in the Ural Mountains,
Siberia, and, abundantly, as water-worn pebbles, in the river and
creek beds of Diamantina and Minas Novas in the state of Minas Geraes,
Brazil. Mineralogists regard the " Braganza," a gem claimed to be a
diamond, included in the crown jewels of Portugal, and weighing 1680
carats, as one of these pebbles; probably one of the finest ever found.
A sobriquet for these clear colourless topazes is " slave's diamonds."
Blue topaz from Brazil is sometimes termed P Brazilian sapphire." A
fine saffron-yellow variety, called " Indian topaz," occurs
infrequently in Ceylon, and rarely, in Brazil; the
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