84 NEW YORK STATE MUSEUM 



the most favorable locality is the pegmatite dike lying along the 

 west side of the gabbro dike on the mountain top i mile south- 

 southeast of The Glen. A single mass of pegmatite there is about 

 25 feet wide and 50 feet long and very rich in orthoclase and 

 albite crystals up to 5 or 6 inches in length, together with more 

 or less quartz and black tourmalin. The nearness to the railroad 

 station and the fact that an old road now extends nearly to the top 

 of the mountain, are features favorable to mining here, but the small 

 size of the exposed mass and the abundance of albite are un- 

 favorable. 



ROAD METAL 



Rock such as that of the diabase dikes of the quadrangle is 

 popularly known as " trap rock," and it takes rank among the 

 finest natural road building materials because of its hardness, fine- 

 ness of grain, homogeneity, and good binding power. So far not 

 a single quarry has been opened in any of these dikes though some 

 of them are large and well situated with respect to roads and good 

 quarry drainage. Among such dikes are those at the west base of 

 Heath mountain (Ingraham farm) ; i^^ miles north-northeast of 

 Pottersville ; and two-thirds of a mile a little south of west of 

 Igerna. Smaller, but well located, dikes are three-fourths of a 

 mile southeast of Kelm mountain and one-half of a mile southeast 

 of The Glen. 



The gabbro masses, especially the more basic ones, would furnish 

 a very large amount of good road material. This rock is hard, 

 homogeneous and rich in iron-bearing minerals to give good bind- 

 ing power. So far but two quarries have been opened in the 

 gabbros and these for State road purposes. One of these quarries is 

 in the south end of the large, coarse grained, gabbro boss on the 

 south side of Loon lake, and the other is in the gabbro boss i 

 mile west of Riverside and near the new State road. 



The basic varieties of syenite, especially those free from mica 

 and low in quartz, would also make good road metal, but no quar- 

 ries have yet been opened in such rock. 



The granite and granite porphyry in general are rather poor 

 road materials because of the high quartz and mica content and the 

 usual deficiency 'of iron-bearing minerals to furnish a good binder. 

 Such rock has, however, been rather extensively quarried at three 

 places for State road work. One of these quarries is situated 

 two-thirds of a mile north of the north end of Loon lake and above 

 the road; the second is along the State road i^ miles northeast of 



