AUGITE-SYENITE AND GRANITELL. 
117 
Tabulation of the results of a microscopic examination of augite-syenites, &c.—Continued., 
Place. 
Specimen number. 
| Quarter-section. 
| Section. 
| Township. 
| Range. 
1864 C | North shore Béte | Near| 35 | 58 |29 W. 
Grise Bay, Ke- 
weenaw Point, 
Michigan. Con- 
glomerate peb- 
ble from Eastern 
Sandstone. 
north 
line 
Macroscopic char- 
acters. 
ee. Sen 
Microscopic descriptions. 
inference from the fact that 
there is in the most deeply 
decomposed places a tendency 
to polarize in large areas; it 
is not impossible, however, 
that this appearance is due to 
the polarization of the finer 
secondary quartz, and that 
these areas are merely quartz- 
saturated matrix, whose 
original spherulitic struc- 
ture has produced the radial 
arrangement of much of the 
secondary quartz. The pla- 
gioclases give angles rather 
low in the labradorite range. 
Where still recognizable as 
plagioclase they never con- 
tain any secondary quartz. 
Besides the finer ferrite par- 
ticles, there are clusters of 
coarse opaque black particles 
—some of which may possibly 
be magnetite—which, from 
their having associated with 
them brightly polarizing au- 
gite particles, may be regarded 
as alteration-products from 
augite. Little seams and 
nests of secondary calcite are 
here and there seen, and, with 
the calcite, occasionally par- 
ticles of epidote. Brilliantly 
polarizing epidote-like par- 
ticles are also seen dotting 
the plagioclases, as if from 
their alteration. 
Closely similar to the section 
last described except in con- 
taining less red staining mat- 
ter. 
Angle between 
maximum ex- 
tinctions of 
adjacent hemi- 
tropic bands of 
the plagioclase 
in sections cut 
at random in 
the zone O: it. 
Angle on 
opposite 
sides of 
cross-hair. 
° ° 
5 4 
3 5 
8 12 
angle. 
E 
° 
