1895. | NEW YORK ACADEMY OF SCIENCES. 33 
The biotite presents no feature of interest except its mode of 
decomposition. At first its color becomes green with diminished 
absorption ; it then alters to chlorite with the formation of lenses 
in the cleavage cracks, made up of an aggregate of small par- 
ticles of a colorless mineral, with high double. refraction, which 
is, in the main, calcite, muscovite being possibly present also. 
At the same time magnetite (?) forms along the cleavage cracks. 
Finally the chlorite and magnetite further decompose to a brown 
earthy mass carrying the alcite lenses. 
Titanite appears in all the slides in the customary rhombic 
cross sections, with an unusually strong pleochroism for that 
mineral. Apatite abounds in the rock as an inclusion in all the 
other constituents in the usual minute, clear, sharply defined 
prisms. Occasional larger irregularly bounded individuals also 
occur with their customary black dust inclusions. 
Pyrite is of frequent occurrence in the quartz-diorite dikes, 
but does not appear in the main body of the rock. 
The microscopic examination suggests that the rock must be 
a quite acid one lying between normal granite and diorite in 
that respect. 
The Schists.—These present no novel features calling for 
especial mention. The actinolite schists are finely fibrous aggre- 
gations of that mineral, the slender prisms seeming to be ar- 
ranged i in two parallel sets which intersect one another at an 
angle approximating 20°. The small interspaces are filled with 
a finely granular mixture of quartz and epidote, and an occa- 
sional grain of plagioclase. 
The mica schists are fine grained markedly schistose rocks with 
abundant biotite, which with irregular grains of quartz makes 
up the main portion of the rock. In two specimens, however, 
orthoclase occurs instead of quartz, accompanied by a small 
amount of plagioclase. Small magnetite individuals invariably 
abound, and all the constituents of the rock are thickly set with 
black dust-like inclusions, which also seem to be magnetite. 
Garnets of a light rose color and with numerous inclusions are 
scattered through the rock. They reach a size of .4 mm. as 
a maximum. Zircon is also a never-failing constituent. 
In two of Dr. Reid’s specimens staurolite occurs in numerous 
short, thick prisms, averaging 6 mm. in length and 3 mm. in 
breadth, bounded by the faces (110), (001) and (610), and with 
both twinnings characteristic of the mineral, that parallel to 
(032) and to (232). It is full of inclusions, notably of quartz 
and magnetite, and in one case a garnet, .3 mm. in diameter, is 
completely enclosed in staurolite, Faidieating the later erystal- 
TRANSACTIONS N. Y. ACAD. Scr., Vol. XV., Sig. 3, January 14, 1896. 
