46 



exclude the necessity of the tetraedrons, which, I believe, 

 have not been found in Silver. 



Thus we have a British specimen of what is reckoned the 

 primitive form of Silver. The matrix of the upper specimen 

 is chiefly Quartzose, with some grey Silver having the Na- 

 tive Silver in spots or blotches, and the Cobalt in a white 

 and husky powder. The lower specimen consists chiefly of 

 Limestone, with minute crystallized Silver among the grey 

 Silver which is represented larger. The rose-coloured and 

 whiter parts are Flowers of Cobalt, or pulverulent Arseniate 

 of Cobalt. 



