THE MINING AND QUARRY INDUSTRY I912 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 is 

 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 his paper " 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 reck 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 io° 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. 



