120 NEW YORK STATE MUSEUM 



up to 30 feet wide. The ore is coarser and more pyritic than that 

 of the Standish. The deposit was worked by the Warwick Iron 

 Co. which ceased operations about 30 years ago. Southwest of the 

 Rayner is the Centennial mine which Hes across the New Jersey Hne. 



Monroe. About 2I miles south of Monroe near Lake Mombasha 

 are the Forshee, O'Neil and other ore bodies which are mentioned 

 by Smock and Putnam as having been worked in 1880, but have 

 long since been closed. The O'Neil mine is notable geologically 

 as being based on a contact deposit in which limestone has been 

 altered to a variety of minerals including chondrodite, serpentine, 

 hornblende, epidote and garnet, affording relations very similar to 

 those at Tilly Foster mine. The ore is lean and large quantities 

 of waste had to be sorted in the production of furnace ore. 



Forest of Dean. This is one of the oldest mines in the Highlands. 

 It has been under operation since 1756, although not continuously, 

 and has reached a depth of 4100 feet on the axis or pitch of the ore 

 which gradually diminishes from 27° near the surface to about 19° 

 at the bottom. In that distance the deposit has maintained its 

 character and general form almost unchanged. A section across 

 the axis shows two wings which diverge above, separated by a 

 wedge of coarse reddish granite; they merge below into a single 

 mass that measures 80 feet across and 50 to 65 feet high from the 

 bottom to the granite horse. The shape may be likened to a 

 synclinal fold with the two wings of the fold abruptly truncated, 

 as shown in the accompanying figure which is adapted from a 

 sketch supplied by Mr H. P. Sweeny, superintendent of the mine. 

 On the outcrop the deposit appeared to be a double vein, the two 

 bodies having a band of granite between, and it was so figured by 

 Mather in his report for the First Survey. Below the surface, 

 however, the body assumed its present proportions and form. The 

 wall rock is biotite gneiss with a northeasterly strike and south- 

 easterly dip, but limestone appears on the footwall side not far 

 away. The pitch of the ore is also northeast, while the footwall 

 approximately conforms to the dip of the gneiss. A band of rock 

 from 1 1 to 8 feet thick, whose exact nature has not been determined, 

 cuts across the southeasterly wing near the base. 



The ore is granular magnetite, often of friable texture and 

 resembling the magnetites of the eastern Adirondacks. Small 

 crystals of apatite are in evidence and the ore is all of non-Bessemer 

 grade. The content of iron averages about 60 per cent. Some 

 sorting is necessary on account of admixture with granite which is 

 found in stringers and small bodies within the deposit and is of the 

 same character as the granite that divides the two wings of the 



