CORUNDIFEROUS NEPHELINE-SVENITE 441 
A specimen of nepheline-syenite was obtained from Lan- 
caster’s farm, some miles west of the locality just described, 
from a small outcrop showing no schistose structure. It is 
coarser grained, but of the same color and general appearance 
as the rock from York branch. Thin sections show, however, 
that it has been subjected to shearing forces, since there is a 
granulation round the larger pieces of feldspar and nepheline 
suggesting mortar structure. Nepheline is present in large 
amounts and also a peculiar type of microperthite having long 
fibrous looking inclusions of one feldspar in another. the main 
mass being in parts very finely striated (anorthoclase?) with twin 
lines making an angle of about 23° with the most marked cleav- 
age. Oligoclase and biotite occur in smaller amounts, the latter 
as usual very opaque. Some of its outer scales weather to a 
bronze-brown color, are dichroic, and have the optical axes much 
farther apart than in the fresh mica. 
Specimens of a medium-grained white rock dotted with 
darker minerals come from a locality not visited by the writer, 
in Methuen township, Peterboro county, and are interesting as 
containing many dark brown corundum crystals having a bright 
bronze luster on basal partings, as well as minute crystals of 
magnetite. 
Thin sections of one specimen disclose chiefly plagioclase, 
finely striated and with a low angle of extinction from the twin 
plane; a little microcline, nepheline and muscovite’ making up 
the rest of the rock. Sections of another specimen very similar 
in appearance contain more muscovite and a large amount of 
nepheline, or rather of a turbid decomposition product, con- 
fusedly scaly or fibrous, having high double refraction. The 
mineral seems to have parallel extinction, fuses readily without 
intumescence to a white glass, and gives water in the closed 
tube, so that it is no doubt a uniaxial or rhombic zeolite, per- 
haps natrolite. The corundum is very opaque so that only 
minute particles of crushed crystals can be studied satisfactorily. 
It contains many inclusions of two kinds, slender black needles 
lying parallel to one another, and brownish-red strips and plates 
