Ilo NEW YORK STATE MUSEUM 
ing biotite and garnet. A camptonite dike cuts the ore body in the 
O’Neill**; this may still be seen on the west side of the cut, 
resembling the remains of a half-ruined wall; but it is gradually 
being destroyed by weathering. 
Although neither limestone nor unmixed Grenville can be found 
in the vicinity, there is no doubt that contact action, or “ contact- 
assimilation ”’ processes, conditioned the locus and character of these 
two ore bodies, the ore having replaced, by magmatic end-stage 
(deuteric) processes, interbedded limestone layers in otherwise more 
or less modified Pochuck-Grenville. 
This is a well-known mineral locality, many specimens having been 
secured from the dumps of these old mines in past years; the mines 
were at one time fairly productive. There is no record of either 
mine having been bottomed, and it is possible that considerable ore 
of good quality could be obtained by proper methods of mining and 
concentration. 
The Mombasha mine. At the northwest end of Lake Mom- 
basha occurs a small cut not more than 4 or 5 feet wide, which 
seems to have been opened on a band of lean disseminated ore, carry- 
ine sulphides. | 
Probably this represents a mere prospect pit, as no ore apparently 
was ever actually mined. The walls of the cut are Pochuck-Gren- 
ville. On the south side of the creek not far from this cut is another 
small prospect pit, with Pochuck-Grenville on one wall of the cut; 
coarse, massive Pochuck-Granite forming the other wall. It is 
possible that these pits may have prospected a series of pockets, 
strung out along the strike of the rock. There is nothing to indicate 
an extensive deposit or any serious attempts at mining. 
MINES IN PUTNAM AND WESTCHESTER COUNTIES 
The Phillips belt. This is probably the most persistent High- 
lands belt of magnetite east of the Hudson river. Along the northern 
end of the belt is situated the Canada Mines group, and on the 
southern extension of it is situated the Canopus mine; the belt is 
approximately 7 miles long, but this does not of course mean 7 miles 
of uninterrupted magnetite. The northern end of the belt is the tnore 
important and, although the magnetite bodies along the belt are not 
thick, they display such a remarkable continuity and regularity of 
outcrop in view of the moderate thickness that persistence likewise 
153 An excellent photograph of this dike and the cut appears in the Report 
on the Geology of Orange County, by Heinrich Ries, 1895. 
