TOPAZ. 37 
peror of Russia contains several fine topazes of this 
description. 
Some of the coarse kinds of topaz are broken down, 
pounded, and used instead of emery for the cutting of 
hard minerals ; and powdered topaz was formerly kept 
in apothecaries' shops, and sold as an antidote against 
madness. 
It is a somewhat singular circumstance, that, if the 
Saxon topaz be gradually exposed to a strong heat in a 
crucible, it will become white ; and, on the contrary, 
that Brazilian topazes by the same process become red 
or pink. By exposure to a still stronger heat, the Bra- 
zilian topaz changes its colour to a violet-blue. 
Jewellers usually divide topazes into the following 
kinds : 
62. BRAZILIAN and SAXON, already mentioned. 
63. BOHEMIAN. These are found chiefly in the tin 
mines of Bohemia, are of small size, deficient in trans- 
parency, have only grey or muddy white colours, and 
are of little value. 
64<. BLUE TOPAZ. This is a large Brazilian gem, 
which varies in size from one or two carats to two or 
three ounces. A fine blue topaz, without flaw, and 
which weighed an ounce and a quarter, was sold for 
200 guineas. It is sometimes difficult to distinguish a 
blue topaz from an aqua marine (68). 
65. PINK TOPAZ. Some beautiful rose-coloured 
varieties of topaz have been brought from Asia Minor, 
and others are found in South America ; but the pink 
topazes in the jewellers' shops are chiefly stones of the 
yellow Brazilian kind, which have had their colour 
changed by heat. 
66. The WHITE, or NOVA MINA TOPAZ, is a per- 
fectly colourless and transparent variety. It generally 
occurs of small size, and is in considerable estimation in 
Brazil for ear-rings, or for being set round yellow to- 
