THE HAVVLEV SCUIST. 1(;3 



All the pyroxene rocks descrilx'd l)elow are ])lainly altered limestone 

 beds in the schist, and, though eonnnon, never reach large dimensions. 



Vyroxene-scMst from Heath. No. 203, Massachusetts Survey Collection. 

 "Augite mica-schist." Ijarge, pale-green pyroxenes, with irregular outlines, 

 inclosing many (quartz veins, and placed in a coarse-granular quartz mass, 

 with much biotite and magnetite. 



Pyroxenic limestone from Sodom Mountain, Southwick. No. 202, ^lassa- 

 chusetts Survey Collection. "Augitic mica-slate." Gi\es abundant efferves- 

 cence in cold HCl, which is renewed on heating. A thin layer of calcareous 

 coccolite between two lavers of cpiartz, the whole inclo.sed in mica-schist. 



The slide shows tlie pale-green pyroxene changing into a white asbestos. 



Pyroxenic limestone from Russell ; railroad cut, east of station and just 

 west of Gr. Frost's. A layer 3 feet thick, of a very tough, fine-grained, 

 reddish rock, showing much calcite, garnet, pyrite, and titanite. In the .slide 

 sahlite is almndant, actinoHte rare. 



INTEUSIVK HOCKS. 



In its southern portion, through (iranville, many pegmatite or coarse 

 nuiscovite-granite veins and masses penetrate the schist, especially in Sodom 

 Mountain, and the same is true in a lesser degree through Blaudford, where, 

 near Mr. Osborn's, the fine rose quartz veins are associated \^ith coarse 

 granite in this series, and in the south edge of the village, where the 

 deeply rotted beds have been much quarried for kaolin. Farther north, 

 across Chester, Middlefield, and Worthington, these coarse granitic vein 

 stones are almost or altogether wanting. 



In the east of Middlefield, and whoUv isolatetl, an enormous dike of 

 porphyritic grauitite runs north and south nearly the whole length of the 

 town, with a width in places of 1,300 feet. It is a rock not unlike the New 

 Hampshire " porphvritic gneisses," but the feldspars are somewhat smaller, 

 10-15'"" in length. Farther north granite is wanting. 



THE II.VWLEY SCHIST. 



This would have been called by Percival, in liis quaint but very effect- 

 ive nomenclature, "a fen-omagnesian formation." The most prevalent rock 

 is a dark-green, soft, chloritic schist, generally crowded with porphyritic 



