46 Elements of Mineralogy. 



It calcines in a ftrong heat, and makes 

 nitre flightly detonnate. If diftilled, it af- 

 fords a fmall portion of vitriolic acid, and 

 fome fulphur fublimes. 



It confifts of about 75 per cent, mild cal- 

 careous Earth, and 25 of pyrites, which con- 

 tains 14 of argill, 7 of quartz and fulphur, 

 and 4 of iron. 



SPECIES XI. 

 Mixed with a notable Proportion of Iron. 



I. VARIETY. 

 Mild Calcareous Earth mixed with Iron. 



Thefe ftones are either yellowifh white, or 

 red : the former are of a fcaly texture, and 

 grow black when expofed to the air, very 

 weighty, effervefce with acids, and contain 

 about 25 per cent, of iron ; the latter are of 

 a coarfe grain, flightly effervefce with acids, 

 lofe 30 per cent, by calcination, and contain 

 10 per cent, of iron. Some ftaladites alfo 

 contain from 20 to 27 per cent of iron. 

 Rinman Mem. Stock. 1 754. Other iron ftones 

 of this fpecies, containing more iron, belong 

 to the calcareous iron ores. 



II. VARIETY. 



