of Boston and its Vicinity. 171 



It is opaque. 



It is crystallized in equilateral six-siiled prisms ; the crystals 

 are small^ and middle sized ; always sini^lc and imbedded. 

 The streak is yellowish grey. 

 It is semi-hard passing to hard. 



The longitudinal fracture is perfectly straight foliated, with 

 a two-fold doubly intersecting cleavage ; the cross fracture is im- 

 perfectly small conchoid al. 



It is moderately brittle. 



It is easily frangible. 



The fraginents are indeterminately angular, and sharp edged. 



The specifick gravity is about 3.200. 



Chymical Character, 

 Before the blowpipe it melts into a black glass 



J- 



Geological Situation and Localities, 

 It occurs imbedded in rolled masses of Basalt, at Charlestowu 



Subspecies TIL — ^Ictynolite, 



Actynolite, Cleavelandy p. 338. Common Actjnolite, Jamemtif vol. u p. 458 

 Schorlaccous Actjnolite, and Common Asbes^toid, Kirivanf vol. i. p. 168. 



Eccternal Characters. 



Its colours are grey and green ; of grey, it occurs greenish 

 grey ; and of green, mountain green, blackish green, and aspara- 

 gus green. 



Its lustre is between shining and glistening, and is between 



vitreous and pearly. 



