26 NEW YORK STATE MUSEUM 



NOTES ON THE OCCURRENCE OF FELDSPAR IN NEW YORK 



It is the purpose of the present notes to call attention to some 

 little known or undeveloped feldspar deposits which were visited 

 in the summer of 191 1 during the course of a field investigation 

 of the granite quarries of the State. A report on the feldspar 

 deposits of the United States was issued in 1910 by the United 

 States Geological Survey. The report, contributed by Edson S. 

 Bastin, contains a very detailed description of the better known 

 local occurrences from which the suppHes of feldspar have been 

 obtained in recent years, but omits mention of those here 

 considered. 



Crown Point, Essex county. The pegmatite occurrence called 

 Roe's spar bed has been a source of feldspar for pottery purposes, 

 having been worked some 15 years ago and the product shipped to 

 potteries outside the State. It has received only fugitive atten- 

 tion in the geological reports relating to Essex county, though 

 mentioned in one of the papers by J. F. Kemp as an important 

 deposit. It is chiefly known at present as an interesting mineral 

 locality. 



The deposit is most conveniently reached from Crown Point, 

 from which it lies about 8 miles distant in a northwesterly direc- 

 tion. It outcrops about i mile directly south of Towner pond at an 

 elevation of between iioo and 1200 feet, as shown on the topo- 

 graphic map. It is now the property of Mr H. W. Willcox. 



The old quarry working shows a face about 50 feet high and 

 75 feet wide in a body of pegmatite which seems rather a lenticular 

 or boss-shaped mass than a dike. The outlines, however, are not 

 clearly revealed by outcrops and there is some uncertainty as to 

 the extent of the deposit. The longer axis appears to run about 

 n. 50° e., as indicated by a series of openings below the main 

 quarry which follows that direction. The width of the exposed 

 part at right angles is from 75 to 100 feet. 



The pegmatite is very coarse and the components well segre- 

 gated. Feldspars with a diameter of 3 feet are not uncommon. 

 They often show crystal boundaries. Quartz is of subordinate 

 importance, but is rather unequally distributed. It is partly of 

 pink color and partly the milky variety. Graphic intergrowth of 

 quartz and feldspar is not abundant. The iron-bearing minerals 

 are chiefly biotite and tourmalin and though fairly plentiful on 



