164 NEW YORK STATE MUSEUM • 



evidence, but the proportion is small. Of iron-bearing silicates, 

 biotite and black tourmaline are fairly common, but for the most 

 part are segregated in bunches, so that their presence would not 

 entail any great waste in sorting for pottery materials. Altogether 

 the pegmatite is exceptionally adapted for the production of feld- 

 spar. 



The face of the quarry is cut by four trap dikes, from i inch 

 to 2 feet thick, which are quite closely spaced and probably coalesce 

 below. 



The main difificulty in the way of successful operation of the 

 quarry seems to be its remoteness. The nearest outlet to the rail- 

 road is by way of Crown Point over a rather rough country, but 

 with the grade favoring the load. 



Penfield Pond occurrence 



A body of pegmatite of large size occurs on the road leading west 

 from near the south end of Penfield pond. It was noted by the 

 writer several years ago, but was not examined with regard to the 

 quality of the materials. 



In the report by Dr Ida H. Ogilvie on the Paradox Lake quad- 

 rangle,^ it is stated that pegmatites are abundant in the vicinity of 

 Crane pond. 



TICONDEROGA, ESSEX COUNTY 



Quarry of Barrett Manufacturing Company 



The Barrett Manufacturing Company has operated a quarry near 

 Ticonderoga for several years past, using the crushed pegmatite in 

 the preparation of sheet roofing. The quarry is situated about 2 

 miles northwest of the village of Ticorrderoga at the eastern base 

 of the ridge of Precambric rocks. The occurrence is very similar 

 to that described near Crown Point, consisting of a large lens of 

 pegmatite included within gneisses of the Grenville series with the 

 larger axis parallel to the strike of the latter, which is about N.55°E. 



The pegmatite is made up of quartz and feldspar which are not 

 very well segregated and do not attain large size, the individual 

 crystals being seldom more than 4 or 5 inches across. The feldspar 

 consists of two varieties, the more abundant being a white or 

 grayish microcline. The second variety is a light green oligoclase. 

 Intergrowth of the quartz and feldspar is the usual condition. The 



1 N. Y. State Museum Bui. 96, 1905, p. 



