THE MINING AND QUARRY INDUSTRY I9II 73 



Another member of the gneiss series, the Forclham, occupies ex- 

 tensive belts in the county ; it is a banded biotite gneiss and finds 

 limited use for local building and rough work. 



Peekskill granite. This is one of the best known constructional 

 granites of the region. It is exposed in two areas about a mile 

 south of Lake Mohegan and five miles east of Peekskill, the two 

 outcrops probably belonging to the same intrusion. The more 

 northerly outcrop is included in the quarry lands of the Mohegan 

 Lake Granite Co. ; the other to the south and nearer Peekskill has 

 been worked as the Millstone Hill quarries. 



The former quarries were opened in 1892 to supply stone for 

 local engineering works and have since furnished large quantities 

 of building stone, chiefly to New York City and for such notable 

 structures as the new Episcopal Cathedral. The granite is a bio- 

 tite-muscovite variety, of medium grain, massive and free of knots 

 and streaks. It occurs in two contrasting colors — yellow and 

 light gray. The rare and very attractive yellow granite forms the 

 surficial outcropping part of the mass, changing to the normal gray 

 at about 50 feet depth. The peculiar coloration is the effect of 

 limonite stain introduced by seepage of ground water, and is not 

 brought about by weathering of the stone itself. The quarries are 

 large and well equipped. There is also a crushing plant for employ- 

 ment of the waste material. 



The Millstone Hill quarries opened in a north-facing ridge, 

 across the valley from the above mentioned property, are owned by 

 Rudiger Brothers, but have been worked until recently by the con 

 tractors of the Croton dam. Besides all the stone used in that 

 structure they have supplied some building material for use in 

 Peekskill and other places. The excavations cover an area of 

 about 500 feet long by 200 feet wide and extend to a depth of 40 

 feet. The granite is of medium grain, very light gray, with more 

 muscovite than that from the Mohegan Lake quarries. There has 

 been little infiltration of limonite, and the gray color persists prac- 

 tically to the surface. The granite is well adapted for building and 

 all general purposes. 



Quarries near Garrison. About five miles north of Peekskill 

 and half that distance south of Garrison is an isolated intrusion of 

 granite which has supplied a considerable quantity of building 

 stone. The quarries were worked by the King Granite Co. and 

 later by Doern & Sons, but have not been active since 1906. They 

 will not be reopened, though there is some prospect of starting 



