EARTHS. SILICEOUS. 57. Adamas. 
57. AD AM AS. Confiding of filica and carbon: 
flightiv ponderous, extremely hard, lamellar, ex- 
hibiting a high peculiar luftre, breakino- iuo in- 
determinate fragments, parafiti al, Ihining in the 
dark after being expoied to the rays of 5je fun, 
attraftmg light bodies when nibbed or heated: 
crackling and iofing its tranfparency in the fire? 
and at 14 or 15® ot wedgewood begins to burn> 
and at length entirely evaporates. 
^ r 0 ^ Diamond. 
A.'jmrn iapidofum. Syji. xii. 3, i. 102 a 6 a 
Gemma pcDucidlffinia. Wall. fyfi. 1. i. ' 
^i .mond. Kir^an miner. Jameljm. u p. 22, 
JO.amona. ichmeij)er mineral \,p,Z 2 Q, 
Cryftallized in the form of prifms. 
The prifms e.ftded, ending both fides in a s-fided pyramid, 
tMth ail the faces convex. 
The pr fms 6 fided, ending both fides in a fi-fided pyramid, 
truncate pyramid. 
vvitl. the f ices of the prifms themfelves unequal. 
The prifms 8 fid.d, with the terminal faces ending in needle- 
ilke pomcf. ® 
Gryftallizcd in the form of double 4-fided pyramids. 
Crvfiallized in the form of 3 fided deprelTcd rough pyramids 
" , faces augmented witha4.fided pyramid at each 
angle tlie common bafe. 
In a rounded form. 
Found in the provinces of Gvkondo and Vi/apour, and at 
mountains in Bengal, in South America, 
in the diftria of Serra do /no in BraBl, generally in loofc fand 
or inclofed in a loamy earth, very rarely aggregate or attached 
to other toflils : of all mtncral luMlanees it pollVfl'es far the 
greareit degree of hardnefs, tranfparcncy and lultre; fradurc 
llriignt and perfedly foliated : it is either colourleis, or red, 
greenifh, yeliowifh, brownilh, black, or Heel blue, withfome- 
nnies fpccks and clouds. It is of all gems the moll precious, 
and irom its entirely confuming like an infiammable fubllance, 
may prooably he confidered as a very pure fpccies of coal. 
