mineralogy. 5 S 
enough orin fiich quantity as is 'neceffary for 
experiments to be made. 
F. The yeliowiili green and cloudy topaz, the 
Chryfoprafe, ^ • 
This is perhaps the fubftance which ferves 
as a matrix to the chryfolite : for thofe I 
have feen of this kind are like the clear- 
veined, called in Swedilh milk efiftai, and 
quartz, which is of the firfl; degree of crif- 
tallifation, 
SECT. XLVn. 
E. Bluifh green topaz, or the Beryll. ^ 
This varies in its colours, and is called, 
when ■ ■ ■ '■ 
I. Of a fea-green colour, the aqua marina, 
¥fhen more green, the Beiydk .. . 
They are found in the Iiream-^works 
in Saxony and Bohemia, in form’ of peb- 
bles, or round pieces. 
SECT. XLVIIL 
D. Emerald. Smaragdus gemma. 
Its chief colour is green, and is U^anfpa- 
rent. I believe it to be, or to have been, a 
criftal of its own feparate principle, fmcc 
in its qualities it differs both from the 
above-mentioned, and from the rock-crif- 
tals \ but I cannot pofitively affert this, 
fince I know no more of it, than that it is 
the fofteft of precious ftones, and that, 
when heated, it is phofphorefcent, like the 
fluors ^ and v/ha.t in Tome cabinets is given 
out for its matrix, and faid to come trom 
. ^'Syp^5 nothing elfe than a deep green 
E 3 cockle 
