174 EARTHS. SILICEOUS. 57. Adamas. 



57. ADAMAS. Confifting of filica and carbon: 

 nightly ponderous, extrenncly hard, lamellar, ex- 

 hibiting a high peculiar luftre, breaking into in- 

 determinate fragments, parafitiral, fhining in the 

 dark after being expofed to the rays of the fun, 

 attradling light bodies when rubbed or heated : 

 crackling and lofmg its tranfparency in the fire, 

 and at 14 or 15^ of wedge wood begins to burn, 

 and at length entirely evaporates. 



pretiosissi' Adamas. Diamond^ 



Muj» Alumen lapidofum. Sy/i. nat. x'li, 3* p. 102. «. 6. a. 



Gemma pcliucidiffima. Wall. fyft. i./>. 230. » i. 

 Diamond. Kirnvan miner. \ ^•393. Jameifon. i^ p^zz. 

 Diamond. SchmeiJJer mineral I./. 220. 



1. Cryftallized in the form of prifms. 



2. The prifms 6-fided, ending both fides in a 3-flded pyramid, 



with all the face.- convex. 



3. The prifms 6-fided, ending both {\6.z^ in a 6-fided pyramid. 



4. The prifms 8-fided, ending in an irregular truncate pyramid, 



with the faces of the prifms themfelves unequal, 



5. The prifms S-Hdcd, with the terminal faces ending in needle- 



like points, 



6. Cryftallized in the form of double 4- fid ed pyramids, 



7. Cryftallized in the form of 3 fided deprefied rough pyramids 



w'th convex faccj^, augmented witha4fided pyramid a.t each 

 angle ©f the common bale. 



S, In a rounded form. 



Found in Boyneo. the provinces of Golcondo and Vifapour^ and at 

 the foot of the Onxa moun tarns in Bengal^ in South America, 

 in the diftrift of Serra dofrio'yxi Brafil, generally in loofe fand 

 or inciofed in a loamy earth, very rarely aggregate or attached 

 to other foffils : of all mineral fuHftanc's jt poiTefl^es far the 

 greateft degree of hardnefs, traniparency and luftre; fratiure 

 itraight and pcrfeftly foliated : it is either colourlefs, or red, 

 greenifh, yellowifii, browniih, black, <:r keei blue, with fome- 

 tipies fpecks and cloudo. It is of all gemi the n:oft p-eclous, 

 and from itf- entirely conHiming like an innanimable fubllance, 

 jpay probably be confidercd as a very pure fpecies of coal. 



