RUBY. 
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colour, subject to vary, and of a lamellated struc- 
ture like the other gems. The best kind of topaz 
is called the oriental, and has the same properties 
as the ruby and the sapphire. It is found in Pegu, 
Ceylon, Arabia, and Egypt. A fine variety of this 
gem is found in Brasil, of a reddish orange colour, 
and of singular brilliancy. Among others which 
are brought from that country are some perfectly 
white, and of so fine a water that Rome de l’lsle 
supposes, with reason, that the pretended diamond 
which weighs twelve ounces, in the possession of the 
king of Portugal, is nothing but a white topaz. 
Saxony likewise produces its topazes, which are 
generally of a straw colour, though they are some- 
times met with white, and sometimes with a blue- 
ish or greenish tint. They are principally found in 
a mountain called Schneckenstein, on the frontiers 
of Bohemia, six leagues to the south of Zwickau. 
From the summit of the mountain rises a great 
rock, about eight feet high, which is composed of 
the same substance as the topaz mixed with other 
stony matters. In parts of this rock there are a 
great number of little cavities, where the topazes 
are found ingrafted in the rock, together with little 
crystals of quartz, and often covered with yellow 
ochre. From the circumstance of so many of these 
stones being found in this place, the German mi- 
neralogists have named it topaz-fels , or rock of 
topaz. Other parts of Saxony likewise produce 
these stones, particularly some granit rocks, which 
