140 Elements of Mineralogy. 



very different compound is generally denoted 

 by this name, I have called it martial muriatic 

 fpar, a name which agrees better with its 

 properties. 



It is of a hard, folid, and fparry texture ; 

 of a grey, ochry, dull colour, but internally 

 bright : it gives fire with fteel, yet effervefces 

 with acids. 



In a ftrong heat it grows brown, but at laft 

 melts perfe. 



100 parts of it contain 50 of filex, the 

 remainder mild magnefia and iron, but in 

 what proportion is not mentioned, 13 Roz* 

 Suppl. 416. 



SPECIES XXIII. 



Siliceous Earth intimately mixed 'with j. of its 

 weight of mild Calcareous Earth. 



Turky Stone> Cos Turcica, 



This is of a dull white colour, and uneven 

 texture ; fome parts appearing more compaft 

 than others, fo that it is in fome meafure 

 ihattery : it hardens with oil ; its fpecific 

 gravity is 2,598 ; it gives fire with fteel, yet 

 effervefces with acids. 



