THE GOSHEN SCHISTS OK FLAGS. 181 



At J. Barber's, in Plainfield, is another very interesting outlier of the 

 Goshen schist. (See map, Ph XXXIV, region west of South Hawley, and 

 section 4 on PI. XXIV ) It is a dark-spangled, garnetiferous rauscovite- 

 schist, and appears across the brook south of the house and strikes N. 2^)° E 

 beneath the house in a broad band. The dark schists thus come in contact 

 with diiferent beds of the older rock as they go north in a way that indicates 

 the presence of an unconformity of some consequence, and the relations of 

 these upper schists to the Shelburne anticline can best be explained by the 

 assumption of an unconformity between them. 



PETROGRAPHICAL DESCRIPTION. 



Garnetiferous muscovite-schist from J Hawke's quany, northwest of 

 Goshen Center The rock is a fine-grained, even-bedded schist, much used 

 for flagging, lead-gray and arenaceous, and is pimpled with garnets and 

 spangled very abundantly by transversely placed scales of black biotite, as 

 is the case with the Bernardston schists (see page 291). The background 

 under the microscope is a colorless mixture of quartz grains and muscovite so 

 fresh and clear that quite thick slides become transparent and the dark-gi-ay 

 color is seen to be due to the coaly grains. The garnets and the biotite are 

 much larger and more abundant than in the newer schists. 



The biotite, which has been called adamsite, phyllite, and ottrelite, but 

 which shows all the optical properties of a biotite (meroxene), is in stout, 

 thick, black crystals, the optical axes only slightly separated, but yet more 

 than in the biotite of the newer schists. 



The garnets are very curiously and regulai-ly filled with quartz inclu- 

 sions of two sizes, arranged differently, and every crystal is the close 

 counterpart of every other. The larger inclusions have exactly the range 

 of shapes of the fluid cavities in quartz. They are often rounded, fre- 

 quently having the shape of a quartz crystal, and are arranged, closely 

 crowded, in triangular planes resting upon the edges of the dodecahedron 

 and meeting at the center. They thus divide the crystal into the twelve 

 segments demanded by the theory of the lower symmetry of garnet, but 

 under crossed nicols every portion of each crystal is perfectly black except 

 where the quartz inclusions shine thi-ough. 



The second group of inclusions starts at the sux-face of an ideally per- 

 fect dodecahedi-on, an eighth of the way in from the sui-face of the crystal, 



