48 ASYSTEMOF 
Pott has ingenioiiily begun, as a bafis for his 
Lithogeognqfia, For want of this, there is no 
other way left, than to confider thefe bodies as 
fimple fubftances (how much foever compound- 
ed they may be), in the following manner. 
SECT. XLIL 
Diamond, Adamas gemma^ 
Which, 
1. Of all ftones, is the hardeft. 
2. Is commonly clear, or tranfparent^ which 
quality, however, may, perhaps, only be- 
long to its cryftals, but not to the rock it- 
felf from which they have their origin. 
3. Its fpecific gravity is neareft 3,500. When 
brought to Europe in its rough ftate, it is 
in form either of round pebbles, with 
ihining furfaces, or of cryftals of an oc- 
toedrd form 
a. Colourlefs, or diaphanous, or the dia- 
mond properly fo called. 
But it alfo retains this name when it 
is tinged fomewhat red or yellow. Be- 
ing rubbed, it difeovers fome eledrical 
qualities, and attrads the maftic. 
The diamonds commonly cryftallize into odoedral 
forms, which, however, often are found fomewhat irregular, 
efpecially when the furface inclines to cryftallize, during the 
Jhooting of the whole cryftal, and alfo when feveral of them, 
unite together into a groupe; in which latter circumftance 
the one hinders the other from alTuming its regular form ; 
and of this I have feen feveral inllances. But the ofloedral 
is not the only regular form which the diamond alTumes | I 
have lately feen a rough diamond, or in its native ftate, in a 
regular cube, with its angles truncated or cut oiF. E. 
SECT. 
