THE CHESTER AMPHIBOLITE AND SEEPENTINES. 87 



The Osborn soapstoue quarry lies west of the house of Mr. W. H. 

 Griswold. Passing west over a few rods of sericite-schist, with two granite 

 dikes and a thick stratum of serpentine, and more schist, all with strike 

 N. 40° W., dip 45° E., one comes upon a bed (No. 11) of black serpentine 

 50 feet thick, which can be followed south a considerable distance along 

 the line of strike and ends abruptly against chlorite-schist along a line at 

 right angles to the strike. 



It is also underlain by the chlorite-schist, and following the line of 

 strike of this south a few yards, across covered ground, one comes upon the 

 large quarries of a soapstone which has completely the structure of the 

 coarse radiated actinolite from which it has been derived, and fresh and 

 partly altered masses of the latter are also abundant, together with large 



N fO W tS£ 



N35 W ^^5 E 



M35 WBOE 



Fig. 5. — Section at Osborn soapstone quarry, Blandford. S S ^ Sahlit«-serpentine ; S ^ Steatite and enstatite-serpen- 

 tine; O S = Olivine-serpentine ; A ~ Amphibolite ; P^ Pegmatite; country rock = sericite-schist. 



masses of coarsely foliated chlorite — a clinochlore with very wide optical 

 angle. The steatite bed is separated by a thin sti-atum (1 inch) of black 

 mica and one of equal thickness of heavy black hornblende-magnetite rock 

 from a dike of granite. 



A small brook runs from this point west tlu-ough the woods, down over 

 sericite-schist, to the bottom of the valley, where it cuts a great bed of 

 peculiar, streaky, black to gi"ay sei-pentine (SS; bed No. 12), derived from 

 a very coarse-grained pyroxenite or sahlite rock, which still shows cleavage 

 faces 20-30°™ square. This bed seems to have been overlooked before, 

 and it is doubtless the source of many of the bowlders found in the south- 

 eastern part of the town. 



The old quarry has been opened during the past summer (1895) quite 

 extensively with improved machinery. The whole width of the steatite 



