86 J. L. Smith on the Emery mine of Chester, Mass. 
“The immediate vicinity of the mine presents a succession of 
lengthened rocky swells with rather precipitous sides, having 
summits between 750 and 1000 feet above the level of the prin- 
es streams by which the hills are traversed. The longer axis 
of the elevations generally coincides with the directions of the 
strata. 
estimated at 750 feet. 
“The emery vein, whose average width may be taken at four 
feet, is situated near the junction of the great gneiss formation 
constituting the western flank of the mountains with the mica- 
orming the eastern slope. T'o speak more exactly, how- 
ever, it lies just within the gneiss, having throughout a layer of 
is rock of from four to ten feet in thickness for its eastern wall. 
Nor does the mica slate advance quite up to this outside layer of 
the gneiss; but in place thereof, an extensive intrusion of tal- 
cose slate occurs, having an average thickness of twenty feet on 
the south mountain, and widening out at the north mountain to 
a breadth of nearly 200 feet as it reaches the terminus of the 
vein, in the bed of the Westfield river. 
“The gneiss, more especially in the vicinity of the vein, is a 
very peculiar rock. It abounds in thick seams of a coarse- 
grained, very black and shining hornblende; and where this is 
not found, it is much veined and penetrated by epidote. The 
stratification is much contorted also; and when the surface of 
the formation happens to be weathered or water-worn, its basset- 
ing es strikingly resemble in color some of the serpentine 
marbles. It is also noticeable that in it quartz is everywhere 
