MAGNETITE IRON DEPOSITS OF SOUTHEASTERN NEW YORK 95 
from the Crossway by the major fault previously mentioned (see 
fig. 9). 
According to Ries**® the ore body consists of several long, 
parallel narrow beds; this can not be verified from surface examina- 
tion at the present time. It was observed, however, that the 
country rock is heavily pegmatized, and it is possible that stringers 
of pegmatite or horses of heavily pegmatized rock split the ore body. 
The walls of the ore body as seen in the cuts are modified Pochuck- 
Grenville, heavily injected in places with pegmatite; the footwall is 
in part coarse Pochuck granite containing bunches and stringers of 
magnetite. The hanging wall is in large part typical Pochuck-Gren- 
ville with more or less disseminated magnetite, and syenite soaked. 
It is made up of a colorless monoclinic pyroxene, a monoclinic 
faintly pink and pleochroic clinohypersthene, plagioclase ranging 
from oligoclase to andesine, a little hornblende, alkalic feldspar 
related to the “soaking” period, and very little associated quartz. 
The quartz occurs chiefly in myrmekitic 1°’ intergrowths; marginal 
intergrowths of alkali-feldspar and plagioclase (symplectite; Seder- 
holm, op. cit.) are likewise in evidence, both types being related to 
the “soaking” period. The footwall is similar except where 
pegmatized and where invaded by granite. 
The ore, 8 feet thick, is massive, rather fine-grained magnetite, in 
places rather closely jointed and blocky. It carries remnants of 
precisely the same minerals contained in the walls (Pochuck-Gren- 
ville remnants), and is clearly of magmatic end-phase replacement 
origin. ws 
Two dikes of pegmatite about 15 feet thick cut the ore body. It 
is stated that the ore in the Patterson (southerly extension of the 
Mountain mine) was about 20 feet thick as mined. No further 
data as to these old mines are available. 
The Crossway (or Causeway) mine. With the exception of 
a small cut about 50 feet long, 4 feet wide and 20 feet deep, situated 
1000 feet southwest of the Crossway workings, called the Fletcher, 
the Causeway (or Crossway) mine is the southernmost working of 
importance on the westerly belt of the Scott group. Ore was dis- 
covered herein 1793 by John Ball***. A 14-foot ore body was 
uncovered, and between 1793 and 1809 some 28,000 tons of ore 
bb) 
ate Ries, Heinrich. Geology of Orange County, N. Y., Rep’t State Geologist, 
YU TSOS. 
137 Sederholm, J. J. Synantetic Minerals and Related Phenomena; Bull. de 
la Comm. Geologique de Finlands No. 48. 
138 Appendix to 3d Annual Rep’t, Dr William Horton’s Report to W. W. 
Mather, 1830. 
