34 Elements of Mineralogy. 



fcaly, fibrous, or granular ; its fliape either 

 regular as cubic, rhomboidal, or prifmatic, 

 confifting of three or five fides ; or amor- 

 phous, of which fort is alabajhr* whofe tex- 

 ture is granular, with fhining particles, and 

 its fpecific gravity 1,87. 



SPECIES III. 

 Combined *witb the Sparry Acid. 



Fluor, Spathumfujibile, Petunfe of Margraaf r 

 2 Tbeil. p. 45, Blue John. 



Its colours are various, being either white, 

 yellow, blue> green, reddilh, purple, brown, 

 or colourlefs ; its texture fparry or fhattery ; 

 its form either amorphous or regular; 

 its hardnefs not fo great as to give fire with 

 fteel ; its fpecific gravity from 3,14 to 3,18 ; 

 if greater it proceeds from a large propor- 

 tion of metallic or other foreign particles. 



It is infolublc in water, does not effervefce 

 with acids, and is fcarcely foluble in them 

 without decompofition. 



When heated it decrepitates and burfts, but 

 does not yield lime, nor harden by the af- 

 fufion of water, as gypfums do. The colour- 

 ed fluors become phofphorefcent when heated 



flowly, 



