6o8 On the Aerated Barytes. 



with a pyramid of the fame number of faces ; alfo 

 the double fix-fided, and the double four-fided 

 pyramid. 



It has a ftrong Glofs or Luftre upon the recent 

 fraclure. 



Its Frafture, in one direction, is ftriated or ra- 

 diated, compofed of fmall convergent fafciculi ; 

 when broken tranfverfely it afTumes a kind of 

 glafly or chonchoidal fradlure, like Quartz. When 

 externalfy cryftallized, its Frafture does not appear 

 radiated in any fenfe. 



It fplits into irregular, rather longifh Fragments. 



The large mafles are frequently compofed of 

 globular concentrical pieces, feveral of them lying 

 one on the outfide of another, and having a round - 

 ifh one in the centre, to which the radii or fafciculi 

 of the reft are pointed. 



It is femi-tranfparent, or diaphanous ; juft fofc 

 enough to admit of being fcraped by a knife. Is 

 brittle, and heavy, but in a fomevvhat lefs degree 

 than the Vitriolated Barytes. Its fpecific gravity 

 has been found to be from 4.300. to 4.338. 



Perhaps to fome, after the cenfure which that 

 excellent chemift Mr. Kirwan has lately pafTed 

 on the utility of external defcriptions offofTils, this 

 delineation of thofe charaflers, by which, without 

 having recourfe to the more tedious chemical ones, 

 the Aerated Barytes can invariably be diftinguilhed 

 from all other foffils, may appear fuperfluous. 

 But many eminent mineralogifts ftill differ in opi- 

 nion 



