34 NEW YORK STATE MUSEUM 



form, and is of gray, white or pink color. When intergrown with 

 the feldspar to any extent it detracts from the value of the latter 

 for pottery use, though quartz has to be added to the pottery 

 mixture. 



The other constituents of pegmatite include biotite and muscovite, 

 one or both of which are nearly always present, and also hornblende, 

 pyroxene, garnet, tourmaline, magnetite, pyrite, epidote, titanite and 

 beryl. Black tourmaline is almost invariably in evidence in the 

 Adirondack pegmatites. These constituents may be of determina- 

 tive importance with reference to the commercial uses of pegmatite, 

 since if disseminated through the body they preclude the extraction 

 of high-grade material. 



The feldspar quarries in present operation are situated in Essex 

 and Westchester counties. In the latter county are included the 

 quarries near Bedford which are the principal producers of ground 

 spar for pottery, enamel and glass manufacture. They are operated 

 by P. H. Kinkel & Son and the Bedford Feldspar Co. The former 

 company produces also a large amount of quartz which is shipped 

 to Bridgeport for manufacture into wood filler. 



The quarries in Essex county which are situated at Ticonderoga 

 and Crown Point produce unsorted pegmatite which is used for 

 roofing material. The Barrett Manufacturing Co. and the Crown 

 Point Spar Co. are the operators. 



The output of feldspar of late years has ranged from 10,000 to 

 15,000 tons annually, but in the last two years has shown a con- 

 siderable advance through the increased shipments of ground spar. 

 In 1912 the product amounted to 24,584 short tons valued at 

 $106,419, by far the largest that had been recorded in the State. 

 In 1913 the production fell off about 25 per cent and amounted to 

 19,680 tons with a value of $99,765. The prices recorded for the 

 product depend upon the quality of the material and the state of 

 preparation. The best selected crude spar brings from $4.50 to $5 

 a ton. Ground spar for enamel and glass manufacture is worth 

 $6 to $8 and ground pottery material $8 to $10 a ton. The unsorted 

 crushed pegmatite sells for about $3 a ton. 



GARNET 

 The production of garnet for abrasive uses represents a special- 

 ized and rather limited branch of the mining industry. Garnet has 

 certain physical qualities which make it an ideal abrasive for some 

 classes of work, notably in leather manufacture, and there is little 



