GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



bed has been exposed and a deep trench blasted through the schists to the 

 west for di-aiuage. The following section is now exposed (fig. 5, p. 87): 

 Commencing at the bottom of the hill to the west, one climbs up 15 rods 

 over coarse chloritic sericite-schists abounding in large quartz lenses and 

 quartz-filled garnets sometimes an inch across. The schists dip 80° E. 

 At 50 feet above the meadow the lower bed of coarse, rudely bedded, black 

 sei-pentinous rock appears (SS). It shows broad, black, lustrous cleavage 

 surfaces of much-altered sahlite, and no specimens could be found where 

 this mineral was still unchanged, such as were procured in the bed of the 

 brook at the former visit. These cleavage surfaces make up the whole 

 surface, or are somewhat separated and the interstices filled with white 

 calcite and magnetite and shot through with tremolite. 



An analysis of the least-altered forms of this rock, which still retains 

 enough of the unaltered sahlite to enable one to make out its optical con- 

 stants, gives the complete formula of serpentine, and is interesting as show- 

 ing, as do all the other rocks of the series, a constant content of nickel and 

 chromium. The analysis was made by Dr. W. F. Hillebrand. 



Analysis of serpentine from Osborn^s soapstone quarry, Blandford, Massachusetts. 



SiO, 



TiO: 



Al;03 



Cr,03 



F&jO) 



FeO 



NiO 



MnO 



CaO 



SrO 



BaO '. 



MgO 



KjO 



Na;0 



Li.O 



H;0 below 110' 

 HjO above 110 



P3O5 



CO.; 



Per cent. 



40.77 



None. 



1.16 



.28 



3.56 



1.47 



.17 



.09 



None. 



None. 



None. 



39.37 



.10 



.14 



Trace. 



.49 



12.48 



Trace. 



None. 



100. 08 



