NOME IV. TUFO. 409 



formed by a black shining glass, which still re- 

 tains the figure of the crystals of schorl contain- 

 ed in the base, which was on the point of fusing 

 into a state of homogenous glass. 



" From the same eruption. 



" No. XIX. A dark grey lava of a rugged 

 fracture, the base of which contains similar 

 scales of talc as No. XIII. and No. XIV. with 

 some laminae of felspar faintly apparent. 



cc Found in large oval masses ejected by the 

 volcano. 



" No. XX. A porous lava, of similar nature 

 to the preceding, with a stratum of vitrifaction, 

 mingled with laminae of mica, radiantly disposed. 

 From the same. 



" No. XXI. A species of stalactite, or con- 

 cretion, found under the preceding lavas - 9 it pre- 

 sents three varieties : 



" 1. With a friable base, and laminae appa- 

 rently of mica. 



" C 2. With a coating of silvery talc. 



" 3. With a coating two lines in thickness, 

 consisting of a white powder, which is salt of 

 Sedlitz, deprived of its water of crystallisa- 

 tion. 



" No. XXII. An incrustation ofselenite, of a 

 mingled white and red colour, in thin strata, 



