126 



TAB. CCCLXVII. 



Cockscomb Pyrites. 



I believe this odd variety is peculiar to England. Kirwan 

 (1st edit.) speaks of it as crystallized in small cubes or py- 

 ramids, united to a common basis " like cockscomb." 

 Dr. Babington and some others mention Cockscomb Py- 

 rites, but some of our late mineralogical authors take no 

 notice at all of it. It is said to be rare, excepting in Derby- 

 shire ; and as it is often very liable to decomposition, many 

 cabinets that once possessed it are now without it. Mrs. 

 Gent of Devizes was so good- as to offer me the use of a 

 finer specimen, that is to say, a specimen with larger 

 cockscomb crystallizations. Both that and mine are pro- 

 bably in a state of slow decomposition, for they are dullish, 

 and have a sulphureous scent, I suppose on account of the 

 Sulphur passing from them. The smoother cubical pyrites 

 and the striated have been considered by some as distinct 

 species, because one is more apt to decompose and fall to 

 pieces, as these and most others often do : this is therefore 

 scarcely a sufficient distinguishing character ; and I have 

 mostvarieties in the changes by oxidizement, from the com- 

 mon brown to the red oxide> and I have British and Irish 

 specimens in cubes, both smooth and striated, resembling 

 those from the West Indies called Sargestum (about which 

 I have had many inquirers) ; and I think, by various speci- 

 mens which I possess of Oxidized Iron, that Pyrites under 

 certain circumstances loses the Sulphur and becomes a solid 

 red Oxide. The present specimen is on a gangue of Car- 

 bonate of Lime with some metastatic Crystals more or less 

 stained or coloured by the red Oxides. Thus they change 

 bv degrees to distinct species at each extremity. This is 

 perhaps a good example to show the difficulty of arrange- 

 ment, and the infinite varieties ; and that we should be cau- 

 tious of indulging too much in little distinctions. 



