36 TOPAZ. 
crystal; of a lamellar or foliated structure, harder than 
yuartz, but not so hard as ruby. 
It varies considerably in its crystallization; is 3| times 
heavier than water ; and, when placed upon any object, shows 
a double image of it. 
The name of topaz is derived from an island in the 
Red Sea, where the ancients found a stone, but very 
different from ours, which they denominated topaz. 
The best topazes are of a deep colour, and are imported 
from Brazil ; the most brilliant ones are supposed to 
be those of Saxony ; but the latter are generally of 
very pale colour. This species, of gem is found in many 
parts of Europe, but defective in transparency, and 
sometimes even opaque. It occurs in large crystals, and 
rolled masses, in an alluvial soil (269), in the upper parts 
of Aberdeenshire, Scotland ; and in veins, along with 
tin-stone, at St. Anne's, in Cornwall. Topazes, more 
than a pound in weight, have been found in Scotland. 
Mr. Mawe speaks of a topaz mine at Capon, near 
Villa Rica, in Brazil. In two breaks or slips of the 
rocks, he says, there were little soft places where the 
negroes found the topazes by scraping in them with 
pieces of iron. He himself observed at least a cart- 
toad of inferior topazes, any number of which he might 
have taken away ; but all that he saw were defective 
and full of flaws. 
These stones vary much in size ; some, particularly 
those of Siberia, being extremely small, and others 
being upwards of an inch in thickness. In the Collec- 
tion of Natural History at Paris there is a Brazilian 
topaz which weighs four ounces and a quarter. These 
stones are not sufficiently scarce to be, in general, much 
valued by the jeweller or lapidary. The deep yellow 
variety is preferred to the pale sort, although the latter 
is often superior to it both in size and hardness. 
Figures have sometimes been engraved on the topaz; 
$nd these, when well executed, are of great value. In 
the "National Museum at Paris there is a superb Indian 
Bacchus engraven on a topaz. The cabinet of the Em- 
