Chemical Examination of American Minerals. 37 



99-680 



These constituents (omitting the alumina, lime, and moii- 

 ture, as accidental) approach very nearly to, 



15 atoms silica, ------ 30 



4 atoms peroxide of iron, ----- 20 



1 atom deutoxide of manganese, - - - 9 



55 



So that Arfvedsonite is a compound of, 



4 atoms pertersilicate of iron, 



1 atom pertersilicate of manganese. 



Thus its constitution is quite different from that of amphi- 

 bole, showing that it is a peculiar species. 



9. FRANKLINITE. 



This mineral exists abundantly at Franklin, in Sussex 

 County, New-Jersey. An analysis of it was published in 1819, 

 by M. Berthier,* who found its constituents, 



Peroxide of iron, - . - - - - 66 

 Red oxide of manganese, - - - - 16 



Oxide of zinc, -------17 



99 



* Annales des Mines, 4"483. [See also a notice of it in the Jour. Acad. 

 Nat. Sciences, Phil. Vol. IV. p. 5. J. T.] 



