88 NEW YORK STATE MUSEUM 
it weathers rusty-red, and in places secondary green iron-sulphate 
is common as an incrustation (melanterite). 
A short distance north of the entrance to the inclined shaft the 
character of the footwall changes from modified Pochuck-Grenville 
to a basic, dark, coarsely granitoid igneous rock made up of color- 
less pyroxene (diopside), olivine, an extremely light-colored mag- 
nesian mica, probably phlogopite, and magnetite and pyrrhotite, both 
clearly end-stage products. The rock is essentially an olivine pyrox- 
enite, and is one of the relatively rare exposures of the most basic 
phase of the Pochuck magma. 
Much rock of this character may be found on the dumps of this 
old mine; occasionally some of it carries such an abundance of oli- 
vine as to be related to the peridotites. A sample of what probably 
constituted a leaner phase of the ore is essentially a magnetite-rich 
peridotite, with much olivine, which is somewhat serpentinized. 
Where serpentinization has affected the olivine, the iron in it has 
been converted to granular magnetite, so that magnetite from two 
sources occurs; that derived from the serpentinization of the olivine, 
insignificant in quantity, and that formed during magnatic end-stage 
consolidation. | 
In addition to material of this character, the dumps furnish 
samples of tremolite rock in considerable quantity. The specimen 
collected by the writer was made up wholly of tremolite and diop- 
side, the tremolite crystals ranging from 0.5 to I centimeter in 
length. 
Although the ore is rather thin, there is no doubt but that this 
subsidiary short belt contains a large quantity of magnetite; the 
chief objection is the high sulphur content, largely pyrrhotite, which 
is difficult to remove. The presence of tremolite rock is suggestive 
of the nature of the material replaced by the magnetite, so that this 
deposit approaches the contact-replacement type, of which the 
Mahopac and Tilly Foster are the best examples. 
The Bering and the Morehead mines. These two old mines 
have not been worked in many years and little is known as to their 
extent or as to the character of the ores. Neither Putnam **’ nor 
Smock **? mentions the Morehead mine, and the only reference made 
by Putnam to the Bering mine is the statement that during the 
census year (1880) it produced 2688 tons of ore. The Bering mine 
is in Rockland county about three-fourths of a mile northwest of 
132 Putnam, B. T. Tenth Census Report, 1880. 
133 Smock, John C. N. Y. State. Mus. Bul. 7. 1880. 
