40 Chemical Examination of American Minerals. 



4 atoms peroxide of iron, - - - 



1 atom deutoxide of manganese, 



1 atom oxide of zinc, _ - _ 



30-25 



We may consider it as a compound of, 



1 atom deutoferrate of manganese, - - 15 



1 atom deutoferrate of zinc, . - - 15"25 



30-25 



supposing the peroxide of iron to act the part of an acid. 



Few chemists would hesitate to consider franklinite as a 

 peculiar species. To what conclusion a crystalographer 

 would come is not so clear. 



10. MANGANESIAN IRON ORE. 



This mineral was sent me by Mr. Nuttall, from Sterling, in 

 Massachusetts. The color is black ; the lustre splendent and 

 metallic. 



It exhibits on some parts of the surface splendent facets, 

 indicating a crystalized state. If any conclusion can be 

 drawn from the position of these facets, the primary form is a 

 regular octahedron. 



So hard as not to be scratched by the knife. Scratched 

 with difficulty by quartz. Streak red. 



Acts feebly on the magnetic needle, but has no polarity. 



Texture foliated ; but cleaves only in one direction. 



Very easily frangible. 



Fracture small, conchoidal. This, together with the color 

 and lustre, gives the mineral something of the aspect of 

 cherry-coal. 



Specific gravity 5"079. 



