38 NEW YORK STATE MUSEUM 



residual more massive portions of the gneisses themselves which are 

 derived from earlier pliitonic eriiptives. Some of the granite intru- 

 sions belonging to the former class are those near Lake Mohegan, 

 Garrison, New Rochelle and Pine Island. The Yonkers gneiss, a 

 slightly laminated pink granite, and the Storm King gray gneissoid 

 granite have been quarried quite extensively. In commercial im- 

 portance the Palisades trap or diabase outranks all the other quarry 

 materials from this section, though it is used solely as crushed 

 stone. 



Feldspar and quartz. In connection with the inspection of 

 the granite quarries opportunity has been given to visit many of 

 thiC pegmatite occurrences which accompany the crystalline rocks in 

 the Adirondaeks and southeastern New York. As sources of quartz 

 and feldspar the pegmatites have considerable economic interest, 

 particularly with reference to the local pottery industry which 

 would derive some advantage from having supplies close at hand. 

 At present practically all of the pottery spar and quartz is brought 

 in from other states, the local production being limited mostly to 

 the commoner grades. The inquiry is still in progress but will be 

 completed as soon as practicable and the results prepared for pub- 

 lication. 



Mineral statistics. The annual review of the mines and 

 quarries for the year 1910 showed a total production by these in- 

 dustries valued at $35,400,257 or a little more than the aggregate 

 reported for the preceding year. Activity was most noticeable in 

 the early months and was followed by a period of dulness and 

 depression, so that as a whole the year was not specially prosperous. 

 In some departments, however, notable gains wxre made. The 

 amount of iron ore hoisted from the mines reached the highest total 

 on record, slightly exceeding one and a half million gross tons. The 

 outputs of Portland cement, gypsum, natural gas and salt also made 

 new records. The effect of these increases on the total was partly 

 counterbalanced by a falling off in clay manufactures and quarry 

 materials, which constitute very important items of local production. 

 In consideration of the general industrial situation during the year, 

 the record may be regarded as very satisfactory. 



Miscellaneous. Brief field trips were made during the year to 

 various localities where new or interesting developments have been 

 in progress. 



The opening of new talc mines in the Gouverneur district and at 

 Natural Bridge afforded opportunity to secure additional data on 



