THE HOOSAC SCHIST. 75 



striated plagioclase appears in limpid grains in tlic yranular quartz jiround, 

 and the rock is the gneissoid development ot' tlic alljitic Iloosae scliists, 

 whose phxees it takes, thougli it did not seem cnnstant enough to furnisli a 

 basis for the division of tlie rock in mapping. 



HORNBLKNUIC HANDS IN THK ALIilTIC MICA-SCIIIST. 



Along the eastern j)ortion of the area, on the east slope of Sodom 

 Mountain, iu Granville, bands of nodules of a ])ale-green actinolite-garnet 

 rock occm', of a type which, so far as I have observed, has al\va^'s Ix-en 

 denved from limestone. 



On the west .slope of the same mountain is a narrow band of ilat, 

 fissile, garnetiferous hoi-nblende-schist of gneissoid structure. The liorn- 

 blende is in black, shining grains, and the mass of the rock is black, but is 

 closely spotted with round, whitish spots 4-6""" in cross-section, in which 

 the hoi'nblende is in larger crystals but much less abundant. Farther south 

 the same rock contains garnets of the same size and arrangement as the 

 whiter spots, so that it seems the hornblende may have been kept out of 

 these spaces by garnets which have since disappeared, to give place to a 

 later development of larger crystals of hornblende. 



THE SHELBURNE FALLS ANTICLINE. 



Nearly everywhere around the Shelburne Falls anticline hornblende- 

 schist seems to rest directly upon the gneiss, and in several places it can be 

 seen to do so, but on the west side, near J. W. Whitney's, there occurs just 

 below the hornblende-schist a white quartzite containing distant scales of 

 biotite, magnetite octahedra, and rutile needles. This may be taken as a 

 possible remnant of the hydromica-schist series. (See section 3 of the 

 Hawley section sheet, PL XXIV.) 



Accessory minerals. — Excepting gai-net, which occurs locally in tlie 

 greatest abundance in large crystals (12-20"""), generally with trape- 

 zoheth-al form, the formation is very poor in accessory minerals. 



Staurolite occurs in quite good crystals, in both forms of twinning, on 

 the road west of Blair's pond, in Blandford. 



Cyanite appears in gray crystals just where the formation crosses the 

 State line on the south, and near the south line of Blandford on the West 

 Granville road. 



