QUARRY MATERIALS OF NEW YORK 8l 



are usually present) constitute the dark ingredients most in evi- 

 dence, but magnetite plays a more important part in the composi- 

 tion than usual in such acid rocks. 



These red granites are perhaps the most available resource in 

 the way of quarry material for general construction purposes within 

 the interior of the western Adirondacks. They have a very wide 

 distribution, with their gneissoid modifications covering a con- 

 siderable but as yet undetermined area. In many places they do 

 not show the uniformity of appearance or other qualities essential 

 to architectural stone, particularly where the intrusions are small 

 and, in the case of the larger bodies, along the contact zones which 

 are often marked by inclusions, segregations and pegmatitic injec- 

 tions. The best locations for quarries are found usually in the 

 central part of the larger masses. 



In southern St Lawrence and northern Lewis counties occurs an 

 extensive and practically unbroken area of the granite which is 

 traversed for several miles by the Carthage & Adirondack Railroad. 

 This is one of the more accessible exposures in the region and is 

 described at some length in the following pages as the Fine-Pitcairn 

 granite. Smaller outcrops are so numerous that there is little object 

 in giving them individual mention. The section about Gouverneur 

 and eastward of there toward Edwards contains many isolated 

 knobs, and the schistose rocks in that vicinity are seamed and in- 

 jected by granite in a way suggestive of the existence of a great 

 underlying body of that rock. At Natural Dam, just west of 

 Gouverneur, a quarry has been recently opened in a small bosslike 

 intrusion for the supply of road metal. The rock is a massive 

 hornblende-biotite granite, but too variable in composition and 

 texture to be workable for architectural purposes. 



The syenite intrusions are of the usual Adirondack type, char- 

 acterized mineralogically by the preponderance of feldspar which 

 is normally of greenish to grayish green color, coarsely crystallized, 

 and mainly the intergrowth of orthoclase and albite called microper- 

 thite. The feldspar constitutes up to 90 per cent of the entire mass. 

 The dark minerals are pyroxene, hornblende and magnetite, of 

 which the last named occurs rather abundantly for a rock of syen- 

 itic composition. Quartz is a very variable component. The pre- 

 vailing dark color gives way to light shades of gray when the 

 syenite has undergone granulation and recrystallization, and in 

 some places to red which lends a certain similarity of appearance 

 to the gneissoid granites. In such crushed phases there are always 



