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durated ftate, colour yellow, grey, brown, or 

 bluilh ; texture fplintery or conchoidal, frequent- 

 ly flaty ; penetrated by bitumen, fulphur, and py- 

 rites. Kirwan. 



b. Limestone with argyllite. 



c. Siliceous Limestone. 



d. Ferruginous Limestone. * 



e. Gypsum with Calcareous Spar ; Gypfum is 

 frequently penetrated with this fpar, fwineftone, 

 fandftone, and perhaps with ftrontian ; which 

 caufe a change in it's hardnefs and gravity, and 

 of colour. from blackim to whitifh grey. 



f. Gypsum with Marl; fometimes difguifed with 

 iron ; colour reddifh brown, and reddifh black ; 

 effervefces with acids; gives a red ft re ak. 



B. MAGNESIAN. 



a. Calciferous Asbestinite. 



b. Steatite with ArgilL 



c. Serpentine with Hornblende. 



d. Siliciferous Potstone ; bluilh black, mixed 

 with white ; it's fracture uneven, partly fplintery, 

 partly flaty ; the quartz in many parts vifible ia 

 the veins. 



S 



c. Ferrugl 



