No. XVI. 



JsTofice of a Kew Crystalline Form of the Yenite of Rhode Is- 

 land. By Dr. G. 1 roost. — Read, i5th October, 1824. 



1 PUBLISHED in the Journal of the Academy of Natural 

 Scier.ces of this city the discovery of the Yenite, found for 

 the fiist time on this side of the Atlantic. The specimens 

 of that mineral which fell under my examination presented 

 only the quadriduodeci7nal and some crystals approaching to 

 the trioctorial and monostique of Hauy. Dr. Mease, one of 

 our memi)ers, lately presented through me a specimen of 

 the Scime mineral to the cabinet of our Society, which con- 

 tained some crystals deviating considerably from the forms 

 mentioned ; but they were so small as to prevent me from 

 ascertaining the value of the angles, and I was therefore not 

 alile to determine their true form. Having since received 

 some specimens through the politeness of Dr. Samuel Ro- 

 binson of Providence, R. I., I found them of the same form, 

 and of a size sufficiently large to enable me to measure the 

 inclination and to determine the form. The crystal in ques- 

 tion is a straight rhomI)oidal prism, the angles being 83° 58' 

 and 96° 2', and the sides forming with the base an angle of 

 90°. I call it 



Prismatic Yenite. (Fer calcareo-siliceux prismaiique.) 



