360 Supposed Neio Mineral Species. 



an angle of 125° 30', and exhibits qualities which prove it iden- 

 tical with those cleavage forms so readily obtained of the min- 

 eral from Phillipstown and Grenville. No cleavage appears in 

 other directions ;* but the mineral on being broken shows an un- 

 even or sub-conchoidal fracture. 



Lustre vitreous, inclining to adamantine. Color dark clove- 

 brown, (St. Lawrence county:) chocolate-brown, (Phillipstown:) 

 light clove-brown, (Grenville.) Semi-transparent to translucent. 



Hardness = 5. 5 . . . 5.75. 



Sp. gr.=3.33 . . . 3.34, (St. Lawrence county ,•) =3. A3 . . . 3.48, 

 (Phillipstown ;) = 3. A5 .. .3.57, (Grenville.) The slight dis- 

 crepancies in specific gravity among the specimens from different 

 localities, probably arise from the adherence of foreign minerals. 



When heated before the blowpipe it affords the same phenom- 

 ena as Sphene. 



From the foregoing description it will be obvious, that the only 

 difference between the mineral under consideration and Sphene, 

 (independently of chemical composition, of which, as yet, we 

 know nothing,) is confined to crystalline form. The attention of 

 crystallographers is now invited to the subject. Should it be ad- 

 mitted, as it appears to me probable, that to reconcile them will 

 be impracticable, we shall then have (apart from the possible dis- 

 covery on analysis, of dimorphism, ) a new species in the varieties 

 here described ; in that event, I shall bespeak for them the name 

 of Lederite, an appellation in which every American cultivator of 

 mineralogy will, I am confident, be happy to acquiesce. 



New Haven, Aug. 31, 1840. 



* With the exception of what is observable in a single specimen, where a per- 

 fectly foliated structure is visible in the direction of a tangential truncation of one 

 of the edges between a and P. The lustre of this cleavage plane is highly- 

 splendent. 



