I 



QUARRY MATERIALS OF NEW YORK 169 



usually predominant, while the microcline is so much intergrown 

 with biotite as to cause much loss in sorting. There is also a little 

 of greenish gray oligoclase. On the east side of the quarry a trap 

 dike intervenes between the pegmatite and the country gneiss. 

 Biotite and tourmaline are the iron-bearing impurities. The latter 

 is in small amount, associated more especially with the quartz. The 

 biotite is rather abundant and in large crystals. 



It would appear that the spar from this quarry might prove ver}^ 

 serviceable for enamel ware and for glazing brick and terra cotta, 

 for which purposes albite is considered preferable to the potash 

 varieties on account of its lower fusing point. 



There are several places in the vicinity of the quarry where 

 pegmatite outcrops. One showing is just northeast, a ledge 30 or 

 40 feet long, with reddish feldspar and some biotite. An 8-foot dike 

 occurs just west of Mr Tyrell's house and contains reddish feldspar 

 and pink quartz, with little mica or other dark silicates. The local- 

 ity may be considered one of the more promising places for ex- 

 ploration for feldspar in this section. 



DE KALB, ST LAWRENCE COUNTY 



Rowland property 



The existence of a ledge of coarse pegmatite in the town of 

 Bigelow, St Lawrence county, was brought to the writer's attention 

 some lime ago by J. H. McLear of Gouverneur. The occurrence 

 is 3 miles northeast of Bigelow, between that place and East De 

 Kalb. It is exposed in natural outcrops rising in low ridges above 

 the general surface. One of the ridges is on the Rowland farm 

 and another occurs on an adjoining property. They are conspicu- 

 ous objects on account of the white color which is contributed 

 both by the feldspar and the quartz. 



The principal ledge is about 75 feet long and 40 teet wide, but 

 these measurements are based on the actual exposure and the 

 body is undoubtedly considerably larger, as there is no evidence of 

 any walls where the pegmatite disappears below the surface. A 

 second ledge is found 300 feet southwest of the first, practically in 

 the direction of the longer axis of the first; and the pegmatite is 

 said to be exposed in other places which, however, were not seen 

 by the writer. There is little doubt that the occurrence represents 

 a large mass of the pegmatite, but whether in a single body or in 

 two or more bodies is not apparent. 



