116 NEW YORK STATE MUSEUM 
But little evidence of the workings now remains; a new road, 
built by Mr Fish, runs across the old dump, which is almost wholly 
obliterated. The old slope is water-filled, and about all that can 
be seen is the brush-grown entrance to it. Nothing is now visible 
of the limestone wall in the pit mentioned by Putnam (op. cit.) ; 
the hanging wall is an extensively modified Pochuck-Grenville. On 
what little remains of the old dump 1s considerable actinolitic rock, 
carrying actinolite, epidote, pyrite, carbonate and granular magne- 
tite; essentially an amphibolite, developed from a highly calcareous 
phase of the Grenville, or possibly from the crystalline limestone 
itself, by contact action. The few odd pieces of ore that still remain 
in the vicinity of the old slope are composed of magnetite, which 
seems to have replaced an amphibolite, since the remnants of silicate 
minerals are chiefly actinolite and epidote, with pyrite, related to 
the magnetite. The deposit seems undoubtedly to have had a contact- 
replacement origin; that is, Grenville limestone, or interbedded lime- 
stone, 1s believed to have been replaced by magmatic end-stage 
emanation products, chiefly magnetite. 
The Croft mine was even more extensively worked than the Todd. 
For 5 or 6 years prior to 1880 it was inactive, but during 1880 the 
mine was reopened and worked until 1881. Since that time the 
mine has been idle. The period of greatest activity was before 1875, 
for the mine is one of the oldest in Putnam county. 
The ore body averages about 3 feet in thickness, with local varia- 
tions ; the old workings consist of a series of pits along the strike of 
the ore, and an open cut about 200 feet long, now badly caved, the 
total length of cuts and pits being about 700 feet. Part way up the 
side of the ridge a shaft, of unknown depth, was sunk, and a few 
hundred feet west of this shaft is an old incline, whose depth is also 
unknown. The ore was apparently followed down the dip at this 
point. At the base of the ridge, and about 100 feet below the out- 
crop, a tunnel was driven, presumably to tap the ore body at a lower 
level and allow the easier handling of the ore, which was shipped to 
the dock in Peekskill on a narrow-gauge railroad. 
According to analyses given in the Tenth Census Report, the ore 
carries from 54 to 64 per cent iron, from 0.005 to .o12 per cent phos- 
phorus, and from 1.047 to 2.018 per cent sulphur. 
On the dump at the tunnel level are immense quantities of actino- 
litic rock, and rock with alternating bands of magnetite and dark- 
green amphibole; curious quartz-feldspar pegmatite, whose feldspars 
contain so much epidote in micropoikilitic intergrowth as to appear 
