THE CHESTER AMPHIBOLITE AND SERPENTINES. 89 



Next east is a bed, 150 feet tliick, of liner-gi-ained chloritic sericite- 

 schist, without garnets, and containing a suliordinate bed of jet-black, flat- 

 bedded ani})hibolite (A), which is made up ahiiost wholly of shiniug-])lack 

 needles, the larger porphjT-itic in a network of the smaller. Eight feet of 

 coarse pegmatite are followed by the same thickness of schist, and this by 

 12 feet of pegmatite, which is separated by a thin layer of reddish schist 

 from the soapstone (S), which is 50 feet thick. On the west border is a 

 thick bed of coarse tourmaline in a matted mass of large clinochlore, with a 

 6-inch bed of coarse biotite adjacent. The eastern selvage is of coarse 

 transverse chlorite in broad plates, which is often crushed to schist. 



The outer sheets of the main soapstone bed are of coarse, matted trem- 

 olite, often radiated and plumose, and more or less changed to talc. In the 

 eastern portion of the soapstone bed is a 10-inch layer of fine actinolite, and 

 at the border these actinolite needles change directly into tremolite. 



The central third of the steatite bed consists of black enstatite- 

 sei-pentine, more or less tremolitic and partly changed to steatite, but still 

 quite hard. This is the first bed of this enstatite rock met with, and it 

 becomes increasingly important as the series is traced southward. Layers 

 of an apple-green serpentine fill fissures in this mass. The superintendent 

 informed me that a 2-foot layer of a black amphibolite, exactly Hke that 

 described above, ran through the soapstone parallel with the strike in a part 

 of the quarry which was under water. The vein of steatite makes a sharp 

 bend of 90° to the east, and bends directly back 90° to the north, and 

 along the east side, where the latter bend is effected, the eastern schist 

 wraps irregularly over the steatite and around a white albite lens, which is 

 enclosed in a thin layer of black, coarse hornblende rock. This bend 

 explains the cutting off of the bed of black serpentine mentioned above, 

 and shows that beyond this sudden fault-like bend the band is less altered 

 to steatite. Indeed, the steatitic alterations may be due to local disturb- 

 ance, as the development of serpentine farther north seems to be caused 

 by faults. 



The next eastern bed is a reddish, quartzose, fine-grained biotite-schist 

 150 feet thick. This is followed up the hillside by 150 feet of a massive, dark- 

 green serpentine (OS), which at the base shows much half-changed olivine in 

 granular masses, separated hj a later tremolitic growth, followed by talc, 

 all of which is beautifully shown under the microscope. This is the only 



