182 GEOLOGY or OLD HAMPSHIRE COUNTY, MASS. 



leaving- this outor band quite limpid, and extends about halfway toward the 

 center, the granules being largest at the surface and diminishing regularlj' 

 to extreme minuteness and arranged in lines normal to the crystal faces. 

 The}- are crowded so densely that they give the crystal the appearance of 

 some hauyne or nosean sections, and by reflected light the red of the center 

 is gradually diluted almost to white at the outer edge, and then framed by 

 the deep red of the outer, clear border. 



The quartz crystals are 15-0.'.20'"'" in size, the larger inclusions 

 0.02-0.03""" and the smaller 0.01-O.OOG""". The causes or forces which 

 brought out this peculiar structure nuTst have operated throughout the rock 

 with great uniformity; must have risen in intensity to amaxinuim and then 

 ceased suddenly, and ha^-e been followed b}" a period when the crystals 

 increased without interpositions of quartz. At the last stage the crystals 

 were built out only at the edges, these being advanced in the sections in 

 bastions, often of great regularity. This is figured in Bulletin No 126, 

 imder "Garnet." 



Staurolite is a regular miscroscopic ingredient, often (piite abundant 

 where it is wholly wanting macroscopically It occurs in single wine- 

 vellow crystals, not often well formed, and is so loaded with large elongate 

 and club-shaped quartz inclusions tliat three-fourths of a surface is often 

 occupied by the latter. Here, also, an outer band is free therefrom, though 

 not luiiforndy so, as in the garnet. 



The biotite, which is usually quite pure, is of later origin and includes 

 garnet and staurolite, and has also an outer clear border. There are thus 

 indications of two times of metamorphism. One may perhaps be connected 

 with the folding of the rocks and the other with the later intrusion of the 

 great granite masses. 



Biotlte-flueiss from tlie crossroad to Buck Hill, Blandford; in Goshen 

 schist. A fine-grained, yellowish rock, with abundant biotite scattered in a 

 sandy quartz-feldspar mass. 



Under the microscope the quai'tz, in grains coated with limonite, seems 

 to be clastic. The rows of pores do not run from one to the other, and are 

 not pai-allel. Rutile trichites ai-e absent. The feldspar, mostly orthoclase, 

 is in grains also coated with limonite, which are at times seemingly increased 

 in size oiUside this coating. Rarely a grain of microcline or plagioclase 

 appears. The biotite, black and fresh, molds the other constituents. There 

 is no trace of anv other constituent, and the rock is as monotonous under 



