196 DESCRIPTION AND ANALYSIS 



elude besides the oxidule of Iron, Franklinite crys- 

 talized in regular octahedrons with truncated edges, 

 Garnets of various kinds, and among others, a black 

 emarginated dodecahedral Garnet, analogous to the 

 Melanite of Monte Somma, Chondrodite, the same 

 variety as exists at Sparta, and also a new variety 

 of the same substance, besides many other interest- 

 ing minerals. 



The present communication is intended to make 

 known a mineral, which an attentive examination 

 made by Mr. Vanuxem and myself, has induced us 

 to consider as a new species. Our observations upon 

 this mineral made separately, and at a distance, have 

 led us to the same conclusion ; and the analysis which 

 I undertook at his request, has fully confirmed the 

 conclusions drawn from its mineralogical characters. 

 The following description includes, besides my ob- 

 servations, those with which Mr. Vanuxem has fa- 

 voured me. For the results of the chemical analysis 

 I alone stand answerable. 



This mineral has hitherto been found in lamellar 

 masses, the largest of which does not exceed a pi- 

 geon's egg, imbedded in Franklinite and Garnet. 



It presents three distinct cleavages, two of which 

 are considerably easier than the third. These clea- 

 vages lead us for a primitive form to a rhomboidal 

 prism, with a base slightly inclined. The angles of 

 the prism are i 06° and 74°, those of the inclination of 

 the base are 94° 45' and 85° 15'. There is another 

 face, which makes with the vertical face of the prism, 

 angles of 110° and 70°. I have likewise seen, in one 



