Mr. William Phillips on the Oa^d of Uranium. 115 



and one specimen of wavellite from Stenna Gwyn near St. Austle, 

 on which some crystals of a light yellow colour are deposited, 

 f But by far the most brilliant specimens of the oxyd of uranium 

 that have been found in this, or perhaps in any other country, 

 were discovered within the last three or four years in Gunnis Lake 

 copper mine near Callington in Cornwall. The gangue of two 

 specimens in my possession is of quartz, bearing the characteristic 

 marks of being the result of decomposed granite, and which is 

 rather confirmed by the circumstance of its cavities being filled 

 with grouan, or decomposed felspar, of a flesh colour; of another 

 specimen, the gangue is wholly a hard gossan. All the crystals 

 from this mine that I have seen are described by fig. 15 ; they are 

 extremely thin, but on some specimens they are more than half an 

 inch in diameter. They are for the most part lying flat together, 

 forming fasciculi which interrupt each other at various angles, and 

 give an extremely beautiful appearance to the group. In Gunnis 

 Lake mine the oxyd of uranium was found at about 90 fathoms 

 from the surface, and in a part of the vein in which gossan 

 abounded. On the few specimens in my possession from that mine, 

 I have not noticed any trace of pecherz, but on those from Tol 

 Cam and Tin Croft mines, particularly the former, it prevail* 

 very much. It is sometimes of a resinous transparency, but 

 is more generally of a dark brown or black, either amorphous or 

 in globules : on several specimens from Tol Carn mine it is quite 

 friable. 



It has already been said that the crystals of this substance from 

 Tol Carn and Tin Croft mines, from which the drawings of the 

 ^accompanying series were made, are for the most part very small j 

 *11 the larger ones are so deeply striated in a horizontal direction, atf 

 -,.:.. p 2 



