36 Chemical Examination of American Minerals. 



rican Philosophical Transactions, and endeavoured to prove 

 that it contained no phosphoric acid, but was merely a 

 hydrous protoxide of iron. The analysis of Godon, how- 

 ever, was fully confirmed by Vanuxem, in his subsequent ex- 

 amination of the mineral, as may be seen in his memoir, 

 published in the Journal of the Academy of Natural Sciences 

 of Philadelphia, Vol. II. p. 82. 



8. ARFVEDSONITE. 



The name Arfvedsonite, has lately been given by Mr. 

 Brooke to a mineral brought by Sir Charles Giesecke, 

 from Kargardluarduk, in Greenland, which had been usually 

 considered as a ferruginous hornblende. For the specimen 

 subjected to chemical analysis, I am indebted to the kindness 

 of Sir Charles Giesecke. 



It had the form of a large oblique four-sided prism, with- 

 out any distinct terminations. The angles of the prism, as 

 determined by Mr. Brooke, are 123'^ 55', and 56° 5'; while 

 in amphibole, the angles of the prism are 124° 30', and 

 55*^ 30' ; constituting a difference of 35'. 



The color is pure black, or in some parts of the edge, 

 having a slight tinge of blue, but none of green. The prism 

 easily splits longitudinally into folia, some of which may be 

 obtained pretty thin ; but I could not procure a cleavage 

 parallel to the summit of the prism. 



Specific gravity of my specimen 3*369. Mr. Brooke makes 

 it as high as 3.44. 



It is softer than the more perfect crystals of amphibole. A. 

 fine black crystal from Finland, which I got from Mr. Nor- 

 denskiold, scratched it distinctly ; but this was not the case 

 with a specimen of common hornblende from Arendal, having 

 a blackish-green color. Its hardness is very nearly the same 

 as that of hypersthene ; but this last mineral has more lustre. 



