74 TRANSACTIONS OF THE [JAN. 23 
They also state that the molybdenite is probably graphite. 
These minerals occur in the bunches of silicates, often of very 
fanciful shapes, that are distributed through the limestone, 
much as is the case with so many exposures of the same rock, in 
the highlands of New York and New Jersey and the foothills 
of the Adirondacks. Although the breast at Van Artsdalen’s 
quarry is 25’ high, a slab 4’ square could not be obtained free 
from these inclusions. At times they strongly suggest meta- 
morphosed trap dikes, and certainly in their mineralogical 
composition recall the results of contact metamorphism. In 
the thin sections prepared from them I have been able to 
recognize hornblende, light green pyroxene, titanite, rutile, 
orthoclase with microperthitic albite, zircon, apatite, pyrite, 
scapolite, and plagioclase. Of the exposures which show near 
the quarry, No. 23 (the numbers refer to the field specimens), 
in E2, is a very coarse, and probably pegmatitic granite ; No. 22, 
on the line between D3 and E38 is norite ; No. 6 in F2 is a decom- 
posed gneiss ; No. 7 is a dark gneiss ; No. 8 is an amphibolite ; 
No.9 contains quartz, pyroxene, and orthoclase, and has suffered 
dynamic strains ; Nos. 10 and 11 appear to be quartzose gneiss 
and have the peculiar blue quartz in them that is characteristic 
of this belt ; No. 12, from the nearest exposure to the west, is a 
decomposed mica schist. No. 7 above contains crushed quartz 
and feldspar, and nests of little green hornblende and biotite 
rods that are the results of dynamic metamorphism after some 
original bisilicate, a few decomposed cores of which remain. It 
seems to have been a pyroxene. The rock has suffered severe 
strains and crushing. The determinations of the other num- 
bers are noted in the description of the map. Outcrops in the 
region are none too numerous on account of the dense, veget- 
able growth, and the high state of cultivation. The norite is 
the most interesting of all. It might ordinarily pass for a dark 
eneiss. The slides show with the hypersthene, green mono- 
clinic pyroxene, hornblende, plagioclase, garnet, magnetite and 
apatite. The hypersthene has the usual pink to green pleochro- 
ism and parallel extinction. The monoclinic pyroxene is light 
green, and is the same as the one which is very common in the 
so-called norites of the Adirondacks. Garnet is in such rela- 
tions to the bisilicates as to suggest some secondary metamorph- 
ism. The hornblende is brown, and is far inferior to the other 
bisilicates in amount. These minerals are very much the same 
as those that have been described in the norites and gabbros, 
that occur near Peekskill* in the igneous rocks of the Cortland 
— — 
*G. H. Williams, Amer. Jour. Sci. Feb, 1887, p. 135, 
