Examination of the Fisher Meteorite. — Winchell. 235 
portion was included in the fragment which furnished the 
powder. Four of these are represented below by the figures 
Nos. 1 to 4. They are constantly dark between crossed nicols. 
except where the small inclusions lie. In fig. 4 at aa are 
brightly polarizing crystallites. This isotrope is less refrac- 
tive than the doubly refracting light mineral as well as than 
the enstatite and olivine. 
Geoup 2. 
3. A glassy-clear mineral, usually free from inclusions but 
not wholly, having cleavage in five directions. Several of 
these are represented by the figures below. Figures 5 and 6 
are the most useful, as they not only show the cleavages but 
also a facial angle of 120°, belonging to a hexagonal prism. 
They each measure a little more than 120°, but as the grains 
are a little inclined upon the vertical axis this excess over 
Geoup 3. 
120° can be neglected. Fig. 5 has this angle L26 degrees and 
fig. 6 127°. The interference figure in No. 6 is simply an arm 
of the black cross, like that of No. 5, but more evident. In 
fig. 7, which is very thick, there are visible two cleavages, and 
the interference figure is indistinct. In fig. 8 the central pari 
polarizes in colors, hut in general it is white. The interfer- 
ence figure is a branch of a black cross. In asmanite up ( a) 
is perpendicular to the easy cleavage and in tridymite from 
