G. H. Williams—Norites of the “ Cortlandt Series.” 135 
minerals associated with phenacite in this pocket are topaz, 
microcline, quartz (smoky and white), albite, fluorite, limonite 
(pseudomorph after siderite), columbite (very rare), and biotite. 
At this pocket the writer found fragments of topaz, albite, 
quartz, and microcline with phenacite attached. On one piece 
of albite were fourteen distinct crystals of phenacite on a sur- 
face about three-quarters of an inch square. 
The largest phenacite ever found in this locality is a rough 
lenticular crystal about 15™™ in diameter. Most crystals are 
colorless, but those that have been entirely imbedded in gangue 
are generally of a faint wine color; one was observed having 
asmoky bluish tinge. All phenacites attached to microcline, 
here, as well as at the Specimen Rock locality, have been on 
the green or amazon stone variety. A few phenacite crystals 
have been observed in the interior of smoky quartz and of 
amazon stone crystals, these minerals showing no evidence of a 
secondary growth. Phenacites have also been found half in 
quartz and half in microcline when the two minerals are in 
contact. Other crystals seem to be of a later generation than 
the original minerals of the cavity, as they occur shghtly 
attached to amazon stone, to albite coating microcline, and 
entirely imbedded in the limonite crust on some feldspars. 
Art. XVI.—The Norites of the ‘ Cortlandt Series” on the 
Hudson River near Peekskill, N. Y.; by Gro. H. WILLIAMS. 
In a former paper on the ‘ Peridotites of the Cortlandt 
Series,”* the writer has described the most basic members of 
that extremely varied and interesting group of massive rocks 
which occupy the northwestern corner of Westchester County, 
N. Y. These peridotites are characterized by the presence of 
the mineral olivine and the almost complete absence of feldspar. 
They are most abundantly developed on the western edge of 
the area occupied by the Cortlandt rocks (Stony Point, on the 
west bank of the Hudson River, and in the southern part of 
Montrose Point) but are also met with at several localities in 
its southeastern portion. Quantitatively they make up but a 
small proportion of the whole series. 
By far the larger majority of the Cortlandt rocks contain, as 
their most important constituent, a triclinic feldspar. Quartz 
and orthoclase also occur in some of them, although these 
minerals are comparatively rare. Other characteristic compo- 
nents are hypersthene, augite, hornblende and mica. Magnetite 
*This Journal, Jan., 1886, p. 26. 
Am. Jour. Sct.—Tuirp Series, Vou. XX XIII, No. 194.—FEBRUARY, 1887 : 
9 
