Chemical Examination of American Minerals. 33 



ago by Dr. Torrey, and labelled Granular dysluite, massive 

 garnet, and franklinite. The locality is Franklin, in New- 

 Jersey. The specimen appeared to the eye, a mixture of two 

 different substances. One of them yellow-colored, semi- 

 transparent and granular, had the appearance of garnet 

 or chondrodite : the other in scales or small plates, had much 

 the aspect of franklinite. It was this last substance which I 

 subjected to analysis, and found to be a sesquisilicate of 

 manganese. 



The color was iron-black, and the lustre metallic. Powder 

 brown, like that of franklinite. 



It was composed of scales or plates laid upon each other, 

 or interspersed through the other constituents of the specimen. 



It was not scratched by the knife, but easily by quartz, and 

 with some difficulty by felspar. The hardness seemed about 

 that of hypersthene. 



Did not act upon the magnetic needle. In this respect it 

 differs from franklinite. 



Brittle and easily reduced to a coarse powder. 



Specific gravity 3-67. But the specimen employed was 

 not quite free from the garnet-looking mineral. 



Its constituents were found to be, 



Silica, 38-388 



Protoxide of manganese, _ - - _ 51*666 



Peroxide of iron, _ _ _ _ _ 9*444 

 Lime, a trace, ------ 



99*498 



If we suppose that the iron replaces a small portion of the 

 manganese, it is obvious that the mineral is a sesquisilicate of 

 manganese, or a compound of, 



I i atom silica, 



1 atom protoxide of manganese. 

 Vol. IH. 5 



