24 CORUNDUM IN THE UNITED STATES. [bull. 180. 
State. The strike of this band of amphibolite is dependent upon the 
windings of the schists, and its dip is approximate^ 7 90°. Its width 
will average only a few rods, but in the vicinity of Chester, a few 
miles both north and south of the town, it is three-quarters of a mile 
wide, and it is in connection with this broad band that the emery is 
found. It occurs on the eastern side of the amphibolite and is sep- 
arated from the sericitic schists by a narrow band of amphibolite, vary- 
ing in width from an inch or two to nearty 18 feet. Sometimes there 
has been considerable serpentinization of the amphibolite, and the 
emery is separated from the schists by serpentine. Across the West- 
field River from the point where the emery is first encountered, the 
amphibolite is replaced by serpentine, and it is in this bed of serpen- 
tine that crystals of this mineral, pseudomorphous after olivine, are 
said to occur, specimens of these being in the geological collection 
at Amherst College. 
The amphibolite is in appearance a finely laminated rock made up 
of interrupted thin sheets of feldspar grains and of jet-black needles 
of hornblende, and usually contains more or less green epidote. 
The sericitic schists on the west of the amphibolite, which are 
described by Professor Emerson under the head of the "Rowe schist," * 
are biotitic and f eld spathic, and often contain garnets that are more 
or less altered to chlorite. The schists on the east are described as 
the "Savoy schist," 2 and are chloritic sericite-schists, mostly of a 
light-gray color, with a shade of green, due to the chlorite that is mixed 
with the muscovite. When the chlorite can not be seen with the eye 
it is readily detected under the microscope. In some places the pro- 
portion of the chlorite has increased until there are considerable 
aggregations of this mineral along the planes of lamination. Garnet 
and pyrite are also abundant in certain portions of the schist. 
The emery vein can be followed for a distance of nearly 5 miles, 
starting from the point where it is first encountered, at the north end 
of the broad band of amphibolite, on the left bank of the Westfield 
River, just above the railroad bridge of the Boston and Albany Rail- 
road. The general strike of the vein is a little east of south and runs 
for the most part parallel to the line of contact of the amphibolite and 
schist. Emery is not found throughout the vein, but can be almost 
continuously followed by means of streaks of chlorite. The vein 
varies in width from a few feet to 10 or 12 feet, the average width of 
the emery being about 6 feet. Upon both sides of the emery there 
are usually developed thin seams of chlorite varying from 1 inch to 6 
inches or more in width. During the early history of the mine a seam 
of feldspar was encountered, about 12 inches wide, lying to the east 
of the emery and bordered on both sides by chlorite 3 or 4 inches wide. 
There is also more or less chlorite developed in the mass of the ore 
body, which varies from some portions that are an almost pure mag- 
1 Mon. U. S. Geol. Survey Vol. XXIX, 1898, p. 76. 2 Ibid., p. 156. 
