Mr. William Phillips on the OxydofTm. 363 



The crystals represented by figs. QQ^ 68, 69, 70, 71, 79, are about 

 the size of a common quill, and were presented to me by a gentle- 

 man of Penzance, who knew not whence they were brought ; 

 judging, however, from a superb specimen in my collection, on 

 which there are some of the above varieties in form, and of about 

 the same size, and which is from Gavrigan stream works in St. 

 Mewan, I presume them to be from the same place. 



The crystals delineated by figs. 72, 73, and 86, are singularly 

 beautiful, and present, though scarcely a line in length, both 

 terminations complete. They were all taken from the same spe- 

 cimen, which is the only one of the kind that I have seen, but 

 from what mine it was brought I am unable to say, it having 

 accidentally been left in London by the captain of a Cornish 

 trading vessel. The crystals represented by fig. 67. were found 

 detached in a vein near the Land's End. 



Of the singular variety, fig. 98. I have four crystals, their form 

 is occasioned by the elongation of one plane of the second modifica- 

 tion on one pyramid, and of the opposed face on the other j they 

 are of a light brown colour, and translucent. 



Eighth Modification, 



This modification, like the preceding, consists in a decrea^^e on 

 each of the four solid angles, caused by the meeting of the two 

 pyramids of the primitive form, by which each is replaced by four 

 triangular planes, placed on the edges, but inclining more than 

 those of the preceding modification on the axis passing through 

 the solid angles, fig. 106. PI. 20. By fig. 107. the planes are 

 shewn in an advanced state. 



The two figures which alone compose the series of this modi- 



2 z 2 



