20 NEW YORK STATE MUSEUM 



are less abundant about Saratoga than the former. They are often 

 somewhat micaceous, a brown phlogopite being the usual mica. 

 Pyrite is also a common mineral, and the pyritiferous quartzites, 

 on weathered surface, have the pyrite weathered out and replaced 

 by a brown limonite stain. 



Much of the quartzite contains graphite sparingly. There is a 

 thickness of at least lOO feet that contains it in sufficient quantity 

 so that it has been worked for graphite at two different localities 

 on the quadrangle, i mile southwest of Kings Station and 2 miles 

 west of Porter Corners. The rock is quite similar at the two 

 places, being granular and considerably altered. It is interbedded 

 with quartzites and quartzose mica schists and is itself a graphitic 

 quartz schist. At the Porter Corners locality the rock is a quartz- 

 feldspar combination, about 50 per cent quartz, 40 per cent feld- 

 spar, and the remainder graphite and mica. In the special bed 

 worked there is but little mica and nearly 10 per cent of graphite. 

 Above and below more mica comes in. The feldspar is very badly 

 altered. 



At the Kings Station locality the rock is so similar as strongly 

 to suggest the identity of the horizon. On first appearance, the 

 rock seems richer in graphite than at Porter Corners, and may be 

 so; but it certainly contains more mica than that, a disadvantage 

 from the standpoint of successful working. The rock in both 

 places is very similar to that which has been worked for years 

 about Hague ; and though it is quite possible that there may be 

 more than one horizon of such graphitic quartzite in the Grenville, 

 it seems more reasonable to assume but one, in default of definite 

 evidence to the contrary. 



Grenville limestone. But two beds of limestone were seen in 

 the Grenville of the quadrangle, one noted only at the dam of the 

 Kings Station graphite mill, the other in two localities, about a 

 mile apart along the strike, between 3 and 4 miles west of north 

 of Kings Station. Each is about 10 feet thick, impure, and closely 

 associated with heavy, black amphibolites, which are very common 

 border rocks to the limestones in the Adirondacks and were origi- 

 nally very impure limestones. 



The limestone of these two beds is far from pure, the calcite 

 constituting not over 50 per cent of the rock. The most common 

 of the other constituents is quartz, but scapolite, pyroxene, phlogo- 

 pite, graphite and titanite are also present. Much of the rock is 

 fine grained and of a gray tint, instead of being the usual, coarsely 

 crystalline, white marble of the region. 



