34 Chemical Examination of American Minerals. 



It is certainly specifically diflerent from franldinite, to which 

 in composition it bears no resemblance whatever. 



Note. The mineral, called by Dr. Thomson sesquisilicate 

 of manganese, is associated with the dysluite, (a mineral an- 

 nounced about five years ago by Professors Keating and 

 Vanuxem, in a paper which they published in the Journal of 

 the Philadelphia Academy *) and a variety of manganesian 

 garnet. It has generally been considered as a modification of 

 franklinite, but Dr. Thomson's analysis determines it to be 

 a distinct species. 



7. DIPHOSPHATE OF IRON. 



This mineral was sent me from North America by Mr. 

 Nuttall. It is found at Mullica Hills, Gloucester county, New- 

 Jersey. The mineral consists of cylinders about two inches 

 long, and half an inch in diameter, incrusted with a yellowish- 

 red sand, which also occurs interspersed through the cylin- 

 ders ; so that they look as if they had been formed in loose 

 sand. The sand consists of grains of quartz, deeply tinged 

 on the surface with oxide of iron. 



The color of the cylinders is bluish-black ; the lustre ^ 

 splendent and glassy. Each cylinder is a congeries of needle- 

 form crystals, radiating from the axis of the cylinder. 



These crystals are easily cut with a knife, and are sectile. 



The specific gravity of a cylinder was found only 1-787. 

 But it was not free from cavities. It contained also several 

 grains of. sand. 



The constituents of this mineral were found to be, 



* Vol. IT. {). 287. 



