MINERALOGY. 
5t 
In confequence of the ignorance I plead in 
regard to thefc forts of ftones, I have given 
this a place by itfelf. 
Saphires are faid to be found in Alfatia, at 
St. Amiarin, but accounts of this kind are in 
general not to be depended Upon, a.s the 
fluors are frequently met with in collec- 
tions and the druggifts Ihops under the 
name of faphircs, when they are of a . deep 
blue colour ; not to mention that the quartz 
is always termed a precious ftone, whenever 
it is found clear, and of a fine colour. The 
faphire is faid to lofe its blue colour in the 
fire. Thofe v/hich are but a little tinged are 
called v/hite faphires. The faphire is feldom 
found of a very deep blue colour, and free 
from parallel flaws which run through it f , 
SECT. XLV! 
C. Topaz. Topazitis^ gemma. 
This is a precious flone, which, when 
rough and perfed, is fold in, a criftallifed 
f The faphires in their rough or native ftate criiiallize 
moll generally like two oblong hexagonal pyramids pointed 
at their tops, and joined at their bales : yet, they are fome- 
times found of an hexagonal columnar form. In the fire they 
lofe their blue colour. 
J have found fome of the deep blue faphires, and fome of 
a milky colour, which, when looked through, varied their co- 
lours in the fame manner as the milky or bluilh opals (Se£t. iv. 
2, 3.) : this is however no reafon Vv^hy thofe opals fliould be 
ranked under the name of faphire, and lefs fo, lince there 
ate alfo agats found of the fame (quality (Seft. I'x. in the note) 
it might rather give rife to a queiHon, whether the name of 
milky or bluijh opal is not to be conhdered as a vague term, 
iince that principal quality is found in Hones of a fomewhat 
different nature, tho* they all belong to the flinty order ? E. 
E 2 form 
