8o NEW YORK STATE MUSEUM 
of the southern belts is probably Precambric, but on the north and 
east within range of the Taconic disturbance, they may belong to 
the early Paleozoic. 
Bodies of practically pure serpentine of considerable extent are 
found on Staten Island and in Westchester county near Rye; they 
represent intrusions of basic igneous rocks whose minerals, chiefly 
pyroxene and olivine, have subsequently changed to serpentine. 
They are not important for quarry purposes, owing to the frequency 
of fissures and joints and the rather somber color of the exposed 
parts of the masses. 
The microcrystalline or subcrystalline limestones that are some- 
times sold as marbles include members of the regularly bedded un- 
metamorphosed Paleozoic limestones, which locally, show qualities 
of color and polish that make them desirable for decorative purposes. 
They range from dense granular varieties to those having a more 
or less well developed crystalline texture and are often fossiliferous. 
Inasmuch as they have never been subjected to regional compression 
or been buried in the earth deep enough to become heated, the crys- 
talline texture, when present, may be ascribed to the work of ground 
waters. These circulate through the mass, taking the carbonates 
of lime and magnesia into solution, and redeposit them in crystalline 
form. Originally, the limestones were accumulations of lime-secret- 
ing fossils or granular precipitates, for the most part of marine 
origin. Some of the localities where these unmetamorphic marbles 
occur are on the west shore of Lake Champlain, around Plattsburg 
and Chazy (Chazy limestone), Glens Falls (Trenton limestone) and 
Becraft mountain and Catskill (Becraft limestone). 
Production. The number of active quarries in the State is small 
and the annual output falls below that of other quarry materials, 
with the single exception of granite. There is considerable fluctua- 
tion, however, in the output, depending chiefly upon the activity in 
building operations, as the greater part of the product is sold as 
architectural stone. A single contract for a large structure may 
make a very apparent difference in the annual total. 
In 1912, there were seven active quarries, with a product valued 
altogether at $241,847. Nearly one-half of the value, or $114,466, 
was reported by three quarries in the Gouverneur district. Two 
quarries in southeastern New York, with one at Plattsburg and 
one at Glens Falls, contributed the remainder. The figures for the 
last three years are shown in the accompanying table. 
