THE MINING AND QUARRY INDUSTRY IQI2 69 
In composition, the rock from this quarry is intermediate between 
granite and diorite. The feldspar in the ground mass is mainly 
plagioclase either oligoclase or andesine, while the porphyritic in- 
dividuals which are ciear and glassy have the characters of micro- 
cline. Quartz is fairly abundant and of smoky color. The reddish 
garnet occurs in scattered grains and large aggregates of grains, 
apparently a secondary development from the feldspar and biotite. 
A green hornblende occurs in small amount. The rock shows little 
weathering, except in the clouding of the plagioclase feldspar, and 
is a strong, tough building material. 
The product of the quarries is mainly building stone which 1s 
cut and dressed by bush hammering at the quarries. The waste 
is used for riprap and crushed stone, a small crusher being set up 
on the property. Shipment is made by Mamaroneck station on the 
New Haven Railroad one-half mile distant from the quarries. 
Campbell’s quarry at Larchmont, which was described by Eckel 
in hispaper “The Quarry Industry in Southeastern New York,” 
has not been worked for a number of years and probably will not 
again be operated, as the vicinity is being rapidly developed for 
residence purposes. The grano-diorite is not so even in texture 
and rather more affected by weathering than at the other quarry 
localities. 
A quarry has been opened along the ridge northeast of Campbell’s 
quarry and one-quarter mile west of the New Haven Railroad. 
It has been idle during the last two or three years, but the waste 
is used in a crusher nearby. It has a face about 125 feet long on 
the strike of the grano-diorite gneiss and from 20 to 35 feet high. 
The rock contains more biotite and is therefore darker in color than 
that at the other quarries in this vicinity, while the foliation is more 
marked, resembling the structure of a typical gneiss. A few small 
bands and lenses of pegmatite afford the only noteworthy variation 
in the exposure. The strike of the foliation is northeast and the 
dip northwest at an angle of 75°. Two systems of nearly vertical 
joints run northeast and northwest respectively, besides which there 
is a fairly well-marked sheeting which dips 10° or so south. The 
joints divide the mass into cubical blocks that average 6 or 7 feet 
in each dimension. The product has been mainly used for build- 
ing and other large structures. There is no equipment on the 
property at present. 
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