178 



Outlines of the Mineralogy and Geology 



Geological Situation and Localities. 



It forms hills in Charlestown, Maiden, Chelsea, Waterto 

 Quincy ; and it occurs in rolled masses, and in larse beds 



Greenstone, at Charlestow 



Grreyvvacke, at B 



and 



Hingham, and in Sienite, at Milton and Braintree 



Use. 



It never separates into tables thin enough for roof state ; but i 



is much employed for the sides, floorings and coverings of drains 



and for many other purposes, where large flat stones are required 



It is extensively quarried near Powder-house hill, in Charles- 

 town. 



Farze^y IL— iSTovacuIite. 



NovacuIIte, Cleavdand, p. 363. Idem, Kirwan, vol. i. p. £38. Whelslate, 

 Jameson^ vol. i. p. 331. Idem, ^ikin, p. 258. • 



External Characters. 



Its colours are g 



grey, and of g 



nd green 

 mountain 



§ 



Of grey 

 een. T 



occurs bluish 

 colours are of 



d with sometimes a tinge of red ; they 



ofl 



ornate with each other j or they are clouded 

 It is dull or faintly glimmering, 

 It is translucent at the edges. 



It is amnrnJinns 



The streak 



s 



It is hard passing to semi-hard. 

 The fracture is fine splintery and 



into undulatins. 



large conchoidal 



; 



pass in 



The specifick gravity is about 



/ 



