171 
The American Geologist. 
March, 1896 
In thin section the stone, aside from the iron elements, ap- 
pears to be principally a granular mass of olivine, more or less 
rusted, and of enstatite, showing- occasionally the chondritic 
structure. The olivine seems to have been entirely shattered 
from its crystalline integrity, and to exist now in the form ojf 
more or h j ss angular cleavage and other fragments impacted 
together and held in place by a secondary cohesion. Still, in 
general the individual fragments are not far removed from 
their original positions, and in some instances are sufficiently 
large to operate on with convergent light between crossed 
nicols. 
The polarization colors are high. Of the numerous sections 
afforded by the slices some are found perpendicular to the 
different axes of elasticity. In one perpendicular to ng (C) 
two cleavage systems are distinctly apparent which intersect 
each other at right angles, although these are crossed by other 
coarse cracks which cut the grain into many irregular frag- 
ments. These cleavages are those parallel to the brachypina- 
coid (010) and the base (001), the latter being less evident 
than the former. Extinction takes place parallel to these 
cleavages. 
Another section is cut perpendicular to nm (b) and has 
a bright bluish-green color. It extinguishes parallel to its 
principal cleavage (010), the other cleavage being reduced, 
by the shattering which the grains have all suffered, to an ir- 
regular series of cross-fractures of the lamellae 010, hardly 
continuous enough to be recognized as cleavage. This section 
is parallel to the base. Other basal sections show no regular 
cleavage. 
Another section, with two distinct rectan- 
gular cleavages is perpendicular to >t/> (a), 
which in olivine indicates a section parallel to 
the brachypinacoid. One cleavage is straight 
and clear, the other is coarse and somewhat 
irregular. Extinction is parallel to these cleavages. 
There are numerous sections which have extinction at a 
varying angle with the cleavage, owing to their obliquity 
with the principal zones. 
The chondri are composed of olivine and of enstatite. The 
various lamellae consist of many individual granules having a 
