452 



Report of the State Geologist. 



rock is a coarse feldspathie gneiss, that on the north Avail being somewhat 

 more quartzose. The rock strikes N. 30 c ' E. Near the west end of the main 

 cut is an olivine eamptonite dike six feet wide, which cuts across the ore- 

 body. The ore was mined out around it and the dike has been left standing 

 like a wall. Another dike of the same rock, or a branch of the first one, is 

 found in the next pit, about 200 feet to the southwest. Just west of the first 

 dike, and next to it, is a coarsely crystalline rock of granitic structure (shown 

 in upper left hand portion of the adjoining figure), and consisting of feldspar 

 and serpentine; the latter, however, is evidently an alteration product 

 of either pyroxene or hornblende, perhaps the latter, as Mather records a 

 syenite rock penetrating the ore-body. 



Next to the ore, the wall rock becomes very basic, and contains a mixture 

 of magnetite and pyroxene, or hornblende. In places, the latter has changed 

 almost completely to serpentine, as in the northwest Avail just east of the 

 dike. In the pit where the second dike occurs, the rock, on the north side is 

 an altered syenite, but next to this second dike the rock is a mixture of 

 calcite, with hornblende or magnetite. Lying in the pit are several masses of 

 calcite, rilled with a reticulation of magnetite streaks. Just what part of the 

 mine this came from could not be determined, but the occurrence of it in this 

 large quantity is somewhat suggestive of a possible sedimentary origin. 



The wall rock is traversed by many joints, and the great masses of rock 

 which have fallen into the pit obscure the relations considerably. Two 

 chambers have been driven at the eastern end of the pit. The mine has not 

 been worked for sixteen years. Probably no locality in the county except 

 Edenville has afforded so many minerals. The most abundant are beautiful 

 little octahedral crystals of magnetite. Pyroxene and amphibole crystals 

 have also been found. 



A list of the minerals which this mine has afforded is given in Mather's 

 report on the Geology of New York, First District. 



The Forshee mines are on a neighboring hill about one-half milt- south- 

 west of the O'Neil mine. The main working is an open pit, about 400 feet 

 long, fifty feet wide and fifty feet deep. The country rock is a feldspathie 

 gneiss striking N. 20° E., and dipping 40° S. E. The ore is very lean and 

 associated with a peculiar pyroxenic rock with a bronze lustre. It very 

 strongly resembles enstatite, but sections of it give an inclined extinction. 

 The lock is very hard and rather coarse-grained. It is traversed in places 

 by quartz veins. The rock at and around the base of the hill is the 

 ordinary grey gneiss. 



