THE CHESTER EMEEY BED. 



141 



A study of thin slides of the rock is given in Bulletin 126 of the 

 United States Geological Survey, under "Oligoclase." 



The width of the emery bed is given as 4 feet by Dr. Jackson in his 

 first article quoted alxive; in his second' he writes: 



The emery veiu enlarges as it goes in, and from 4 feet Las already widened to 7 

 feet 8 inches of solid emery of the best quality. The adit is now extended 2G0 feet. 



In a limited portion of the working in the lowest shaft (see fig. 7, 

 below) the rock can-ies diaspore in large quantity and of tlie finest color, 

 especially the isolated crystals resting in open fissures ujjon and partly 



PLAN OF NEW DRIFT NORTH OFTHE ROAD 

 Drift 



Fig. 7 — Section of old emery mine, Chester. Section of the main mine south of the road and plan of the new mine north 

 of the road. All drifts are in amphlbolite except where emery is indicated. 



inclosed in crystals of conindophilite and shot through and overgrown with 

 delicate needles of rutile; and radiated crystals of epidote and rarely of 

 brookite^ were of exceptional beauty, both of form and color. The diaspore 

 presented square prisms 25-30"" in length, finely terminated, of rich violet- 

 tinted hair-brown color. It occurs also in compressed, rounded masses quite 

 within the substance of the emery.' 



I am indebted to Mr. Judson Thomas, superintendent of the emery 



' Am. Jour. Soi., 2d series, Vol. XLII, 1866, p. 107. 

 2 Shepard's Report Emery Mine, 1865, p. 12. 

 =Ibid, 1865. 



