54 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



red crystals show at times a sharp prismatic cleavage, beiug ofteu very 

 irregular lobed masses and ofteu verj^ regular crystals with shining faces. 



The andesite (Shepard's type) crystals are about 20 by 10 by 10°"°, 

 not bounded by distinct faces, but embedded in a granular, compact mass 

 of anorthite, translucent and bluish-white, with many small scales of biotite 

 intermixed. Sections cut parallel to P, oc P (x, and co P S; were much 

 decomposed and impreg-nated with scales of muscovite, placed ])rincipally 

 in the planes of principal cleavage and in esjiecially large plates parallel 

 to 00 P &. It is poly synthetically twinned parallel to oo P o6 in broad 

 continuous plates of equal width; extinction on cc P dc, — 13° to — 14°; 

 on P, — 4° to — 5°, agreeing thus exactly with andesite 



4. Serpentine from Pelham, about 100 yards west of the "asbestos'' 

 mine. Dull black-green serpentine, changed an inch deep into white talc 

 and showing deep in the interior "ph8estine"-like aggregations of talc, from 

 alteration of the bronzite. 



Slides cut — (a) from the outer talc layer, (p) from the layer of transi- 

 tion, (r) from the interior deep-green serpentine — showed: 



(«) A mass of wavy talc scales containing remains of bronzite, with 

 long jet-black hairs, slightly curved, placed parallel to the vertical axis of 

 the bronzite and ending on the mass of talc scales into which the mineral 

 is decomposed; (h) a matted mass of actinolite fibers of pale-green color, 

 very strongly dichroic; (c) a mass of actinolite fibers and talc scales, with 

 small portions of serpentine and in places with grains showing the olivine 

 network, the whole having the outward aspect of a common serpentine. 



The specimens labeled "Black serpentine and talc, Pelham, Mass.," 

 No. 132, in the Massachusetts State Survey collection of President Hitch- 

 cock, is from the above locality. 



5. Epidote-gneiss fi-om Pelham; asbestos quarr)'. An even, fine- or 

 medium-grained mixture of flesh-colored orthoclase, gray quartz, and bright 

 pistachio-green biotite, with small black grains of tourmaline. 



Under the microscope the epidote is scattered in long crystals exactly 

 like the plagioclase in a diabase. Minute veins are entirely filled with 

 epidote; only orthoclase is present as a feldspathic constituent, and around 

 nuclei of this broad bands of epidote needles are aiTanged parallel to the 

 former clea\'age planes or outlines of the feldspar, showing the nucleus to 

 be only a remnant of a larger crystal. 



