184 GREEN MOUNTAINS IN MASSACHUSETTS. 



of Sugarloaf mountain; 494, between that mountain and Round rocks; 

 324, on the line of contact between the Stockbridge limestone and the small 

 mass of the Berkshire schist south of Sugarloaf; 474, in the deep cut 

 between cast and Potter mountains; 475, at the southwest end and foot of 

 East mountain in Hancock; and 703, at the triangulation point on the north 

 summit of East mountain. 



More rarely garnets occur, giving rising to chlorite. Thus at locality 

 40, on the tongue of schist north of the Adams quarries. Garnets occur 

 also in the small isolated schist mass west of Lanesboro village. 



The graphitic schist of this horizon was early noticed by Emmons 1 and 

 Hitchcock. 2 It generally occurs near the underlying limestone, as about 

 New Ashford, at locality 274, and near Maple Grove station, locality 139, 

 on the east side of Greylock. The graphite is in microscopic, irregular 

 layers, or in masses, surrounded by even sized quartz grains and scales of 

 graphite and muscovite. 



Octahedral crystals of magnetite are in many places scattered through 

 the schist, 3 but the most characteristic minerals are albite, interleaved 

 ilmenite and chlorite, and graphite. 



The rock is sometimes calcareous, but not continuously so. Rarely 

 veins of calcite and chlorite traverse it, Between New Ashford and Lanes- 

 boro a graphitic limestone occurs in the schist, containing angular, often 

 rhombohedral, crystals of albite partially replaced by calcite. 



THE BELLOWSPIPE LIMESTONE. 



For structural reasons the Farnham's quarry limestone has been placed 

 here. That limestone is generally white (though sometimes gray) and highly 

 crystalline, like the Stockbridge limestone; but in the other areas of this 

 ton nation the limestone is finer grained, less often white, frequently argilla- 

 ceous, micaceous, or pyritiferous. Frequently the micaceous element pre- 

 dominates and the rock is a calcareous schist, and in several localities the cal- 

 careous element disappears altogether. Galena, zinc blende, and siderite 

 occur along with pyrite in the limestone of the Bellowspipe. Associated 

 with these limestone and calcareous schists are beds of slightly micaceous 



1 Geology of Second District, New York, p. 153. 



2 Final Report on the Geology of Massachusetts, p. 581. 

 'Emmons, Geol. Second District, New York, p. 111. 



