1 



of Boston and its Vicinity, 



•J 



The fragments are splintery and indeterminately angular 

 Its specifick gravity is 3.64. 



155 



Chymical Character, 

 Before tlie blowpipe it melts into a black porous slag. 



Geological Situation and Localities. 



It occurs disseminated in rolled masses of Granite at Cam- 

 bridge, Brighton, &c. &c. 



SPECIES \,—FELDST.m. 



Common Feldspar, Cleavelandy p. 266, Idem, Kirivan^ vol. i. p, 316. Idem, 

 iilcin, p. 212, Fresh Feldspar, Jameson, vol. i. p. 279. 



External Gharacters, 



Its colour 



white 



white, yellow, red, brown, and black 

 Byish white, and reddish white; of ye 



Of 



cream yellow ; of brown, light red brown ; of red, aurora red and 

 flesh red ; of black, velvet black. 



Its lustre is shining approaching to splendent, and is vitreous ; 

 sometimes dull. 



It is opaque, or slightly translucent at the edges. 



It is amorphous and crystallized in tables and rhombs, whose 



angles are often truncated. The crystals occur single or variously 

 aggregated ; they are small and very small, and are often hollow. 

 It is hard. 



The fracture is foliated, the cross fracture is fine si'ained un- 

 even, and fine splintery. 

 It is brittle. 



; 



1 



i 



