ANNALS 



OF 



PHILOSOPHY. 



OCTOBER, 1824. 



Article I. 



On a new Mineral Substance. By Mr. A. Levy, MA. of the 



University ofParis. 



(To the Editors of the Annals of Philosophy .) 



GENTLEMEN, Newman-street, Oxford-street, Sept. 17, 1814. 



Mr. He ulan d had put aside a long time since a specimen of 

 Mr. Turner's collection, from the Bank mines, in the government 

 of Ecatherineburgh, in Siberia, considering the small emerald 

 green transparent crystals which are upon it as differing from 

 any described substance. Upon detaching and measuring some 

 of them, I have ascertained that their form was incompatible 

 with those of the arseniates and green carbonate of copper, 

 with which their external characters bear some resemblance, 

 and I am led, therefore, to consider them as belonging to a new 

 mineral species, to which Mr. Heuland proposes to give the 

 name of Brochantite, in honour of a mineralogist as well known 

 here as in his own country. 



The appearance of the crystals is that of thin rectangular 

 tables, bevelled on the edges with the angles truncated, such as 

 is represented by fig. 7 (PI. XXX II). Their colours are emerald 

 green, they are transparent, and their hardness is about the 

 same as that of green" carbonate of copper. The planes M are 

 blackish and dull; all the others are brilliant and fit for measure- 

 ment by the reflective goniometer. I have not been able on the 

 very minute crystals I have examined to ascertain the directions 

 of the planes of cleavage, and I have, therefore, assumed as the 

 primitive aright rhombic prism, fig. 6, the lateral planes of which 

 correspond, I believe, with the planes marked M, fig. 7. The 

 planes e s and a 1 are then the results, the first of a decrement by 

 four rows on the angles e of the base of the primitive ; the other 

 of a decrement by one row on the angle a. The angles I have 

 Sew Series, vol. vih. R 



