90 Elements of Mineralogy. 



gives fire with fteel . it emits a ftrong fmell 

 when heated, and fometimes without heat 5 

 does not fhew white when fcraped. 



SPECIES IX. 



Argill mixed with from 3 to 4 tenths of its 

 weight of Si/ex, and a little of the yellow or 

 red Calx of Iron. 



I. VARIETY. 



Argillaceous Shift us ^ Flag ft one. 



This is of a grey, yellowifh, or reddifli 

 white colour ; does not give fire with fteel, 

 nor efFervefce with acids : its fpecific gravity 

 is from 2,6 to 2,78 : it is in fome places ufed 

 for covering of houfes, but moftly for floor- 

 ing : it is fometimes compact, and fometimes 

 fandy, like the next variety, and then its fpe- 

 cific gravity is fmaller. 



II. VARIETY, 

 Argillaceous Grit^ Free-ftone> Qr Sand-ftone. 



It is called free-ftone becaufe it may be cut 

 eaf^ly in all directions : its texture is more 

 or lefs po ous, equable and rough to the 

 tout h : it exhales an earthy fmell when frefh 

 broken and breathed upon : it does not give 

 fire with iieel, nor efFervefce with acids. 



That 



