Calcareous Genus. 53 



SPECIES VI. 



Compounds of Calcareous Earths 'with Species 

 of two or more Genera. 



I. VARIETY. 



Calcareous Porphyry. 



This confifts of quartz, felt fpar, and mi- 

 ca, in feparate grains, united by a calcareous 

 cement. 



II. VARIETY. . 



Limeftone inter fperfed with Shoerl and Mica. 



CHAP. IV. 



Barytic Genus. 



SPECIES I. 



Ponderous Earth combined with the Aerial 

 Acid) aerated Barofelenite. 



Dr. Withering prefented me with a very 

 pure fpecimen of this fpecies from Alfton 

 Moor, in Cumberland. It much refembles 

 alum, but its texture is ftriated : its fpecific 

 gravity is 41331* though when this com- 

 pound is artificial its fpecific gravity is 

 only 3>773, according to Mr. Bergman\ 

 evidently becaufe it contains much water, 

 E 3 for 



