Geology and Mineralogy. 161 



graduate into killas or clay-slate. These slaty crystalline rocks 



are Mulsh-green to greenif-h-gray ; an,! the slaty structure is some- 



slightly opaque l.asc, au.l with occasional patches of quartz, and 

 sometimes magnetite. An average slaty kind of a dark color 

 gave on analysis the results in column A below. A rock ol grayer 



the ivsults in column B. 



(A hornblende of Botallack, Cornwall, having sp. gr.=:-;--U, 

 afforded V , !>■ n. — nI , i ,1 i 



lime 12-31, \ ! i=100*09.) 



gray and I amborne, 



Mseenunde , of column 



D- Another, from North Huel Rose, in Newlyn East, was grayish, 



it are stratified, with 

 ""'•'■ ' " ' "' ' ty ? le * va - e - • altered a bbro 



■ ■ : . . .'• • .. • 



^ late8 « f he western 



:■■■■■■■.■ ...... ' 



