of the red oxyd of Copper and arse mated Iron. SI 



Jewell ; in chlorite, and In brown and almost pulverulent mica in 

 Huel Gorland. The crystals enclosed in the latter substance, it may- 

 be observed, are always of remarkable brilliancy and in well defined 

 varieties. In the latter mine it also occurred with blue and green 

 carbonate of copper ; with fibrous arseniate of copper ; in cubes 

 with the green cubic arseniate of iron ; with mispickel and pyrites. 

 I possess one specimen from Cornwall, but from what mine is uncer- 

 tain, in which it is accompanied by vitreous and yellow copper. It 

 has been found in capillary crystals in Huel Gorland, Carharack and 

 Tol Carn mines ; in the latter in recomposed granite though but very 

 sparingly. I have one specimen from Tin Croft mine, in which the 

 red oxyd Is intermingled with native copper, and with jasper of a 

 fine red colour. 



There are perhaps but few minerals that exhibit so many beautiful 

 ■and regular forms, although the modifications of its primitive crystal, 

 -hitherto noticed, are only six in number. Of these forms, four have 

 been given by Haiiy, which, with two or three delineated by 

 Sowerby in his British Mineralogy, constitute the whole of what has 

 been published relative to the crystallographical history of this inte^ 

 resting substance. My own attention has been particularly diredled 

 to this subject, by the possession of a large collection of specimens, 

 chiefly from Huel Gorland mine ; from which have been selected the 

 principal varieties in the form of the crystal, which are here presented 

 in a regular series. The number of these will doubtless be increase^ 

 by future research. It does not seem requisite to offer detailed 

 remarks on each individual crystal ; it will suffice to make some 

 occasional observations, and to note some peculiarities that might not 

 be perfectly intelligible by the assistance of the figures alone. 



