DOMAIN VIII. DIAMICTONIC. 



a different appearance: thus the lime-stone, 

 Leske, s. 1769, seems as if passing into horn- 

 stone, and is of a yellowish grey colour. Lus- 

 tre, 0. Transparency, 1. Fracture, fine, splin- 

 tery. Fragments, 1. Hardness, 9- Sp. gr. 

 2,640. It effervesces briskly with acids, but 

 melts into a greenish grey compact enamel. 



" Effervescence with acids is not therefore a 

 sufficient proof that a stone will burn to lime ; 

 thus the dark bluish-grey stone, Leske 0. 1229; 

 whose lustre is ; transparency, ; fracture, 

 uneven and splintery ; fragments, 2 ; sp. gr, 

 2,740 ; hardness, 9 ; and which contains the 

 impressions of various shells, and effervesces very 

 briskly with acids, yet melts into a black com- 

 pact glass. It has an earthy smell when breathed 

 on."* 







NOME XXVIII. GYPSUM, WITH MARL. 



I 



[VAUQUELITE, from Vauquelin, 1800.] 



Gypsum often forms veins in hardened clay 

 or marl, and is sometimes penetrated with the 

 latter substance. Instances may be found at 



the Old Passage, near Bristol. 



/ 



* Kirwan, i. 373. 



