C *34 3 

 C. ARGILLACEOUS. 



a. Argillaceous Sandstone ; amorphous, flaty, 

 and compaQ; does not efFervefce with acids; often 

 fhot through with mica ; make mill-ftones, filter- 

 ing-ftones, and coarfe whetftones; compofed of 

 argillaceous cement, with fragments of quartz, 

 feltfpar, and flint. 



' 'ft %>'}Lr . 



b. Ruddle Stone; amorphous, flaty, and com- 

 paQ:; containing argillaceous cement, with quartz, 

 filiceous fchiftus, or hornftone and argillite. 



c. Argillaceous Porphyry ; amorphous ; con- 

 tains feltfpar in indurated clay ; hornblende, trap, 

 wakken, mullen, krag, or argillite. 



d. Amigdaloid; amorphous ; containing round- 

 ed mafles of calcedony, agate, zeolite, calcareous 

 fpar, lithormaga, fteatite, green earth, &c. in an 

 argillaceous bafis. 



e. Schistose Mica ; amorphous, flaty ; con- 

 tains mica and quartz. 



D. SILICEOUS. 



a. Granite ; amorphous, compact, flaty ; chiefly 

 compofed of quartz, feltfpar, and mica; the com- 

 paQ; parts generally irregularly mixed, and of va- 

 rious fizes. 



b. Sienite; amorphous, compaQ, flaty; com- 

 pofed of quartz, feltfpar, and hornblende; or of 



quartz*. 



