54: NEW YOKK STATE MUSEUM 



invariable presence of the pyroxene and other silicates leads us 

 to infer that the original limestone was an impure siliceous 

 variety, and when metamorphism affected it, the silica, lime, 

 magnesia and iron present, became combined in the included min- 

 erals. The limestones furnish the only localities attractive to 

 the collector of minerals and some advice regarding them is 

 given later under the head of mineralogy (p. 63). In fact loose 

 bunches of pyroxene crystals, garnets and other characteristic 

 aggregates and masses of black hornblende often remind us when 

 doing field work that limestones must be near before the actual 

 outcrop is discovered, 



Quartzite. In two or more localities small outcrops have been 

 met of a rock that seems to be excessively altered sandstone. One 

 is on the old road from North Elba to Keene,and is in Keene tawn- 

 ship; the other is at the Red Rocks on the east side of the Keene 

 valley. Additional ones of small size are met in a minor degree as- 

 sociated with the limestones of the Keene-Jay valley. The rock 

 appears to the unaided eye to be an aggregate of little else than 

 quartz grains through which flakes of graphite may occasionally 

 be detected. When cut in thin section the rock from the 

 old Keene road shows much emerald green pyroxene, and a 

 little scapolite. All the minerals are strained and fractured and 

 have clearly been subjected to great pressure. The outcrops 

 in the two localities specially cited are in or near steep precipi- 

 tous cliffs, that have been produced by faults. 



The quartzites were doubtless originally sandstones that had 

 sometimes carbonaceous matter, and sometimes lime, magnesia, 

 iron and alumnia, sufficient in amount to yield the acces- 

 sory minerals. Along the old Keene road the quartzite passes 

 almost imperceptibly into a gneiss, that may Itself be an altered 

 sediment. 



Granite. In four localities a rock has been met that corres- 

 ponds to granite. One is on the steep sides of a spur of Mt Whi te- 

 f ace along the trail from the north end of Lake Placid to Franklin 

 Falls. Another is at the High Falls in Wilmington Notch in the 



