STONES. 
2 73 

L A 
P I D E S. 
S T 
ONES. 
Cpalus Gemma. 
The Opal. 
Cos Damiatze. 
The Whetftone of Damiata. 
^atrum tEgyptiarum. The Nitre of the An- 
cients. 
*’T"^ El E Opal is one. of the rareft Gems to be 
X met with. During my {lay at Alexandria, 
J was Ihewn a done by Mr. Roboly, the French 
Interpreter, which was of the fize of a hazel-nut, 
, ltl the form of a half globe, and fet in a ring; if 
lt was held horizontally, it had a very fine olive 
c °lour ; but if it was held perpendicularly, between 
l he eye and the light, it had the colour of the finelt 
*nby. The prefent poffeffor had procured it by 
Occident from a Peafant, who found it amonglt 
old ruins, and fold it for five or fix pence. 
Che Interpreter, who knew not what it was, let 
great value on it, and alked me, whether I 
^new the ftone, and how much I thought it 
"'orth ? I anfwered, that it v/as an Opal but 
c °uld not tell him the worth of it, as 1 was not 
"kd to prize fuch things, the value being often 
^portioned to the talfe and inclination of the 
Putchafer ; I however told him, that it was worth 
" av ing and keeping, and might be of confiderable 
Va lue to a perfon who was fond of Gems; this being 
T one 
