102
Figure 23. Backscattered electron image, X-ray images, and stereogram of augite grain
CPX300 from sample 97NSM203. a. Backscattered electron image of CPX300.
Chemical zoning in the grain is faintly apparent. Compositional traverses 1 and 2 are
labeled “T1” and “T2,” respectively (Table A1.2, analyses 11-35 and 36-55,
respectively). b. Stereogram of CPX300 (upper hemisphere projection). The stereogram
is rotated 180° about A1 relative to the measurements presented in Table A3.2. The optic
plane is shown as a solid curve, while the indicatrix YZ plane is shown as a dashed curve.
The grain is oriented such that the c-axis is at high angle to the plane of section; the grain
produces a slightly off-center optic axis figure. Though fine exsolution lamellae of
orthopyroxene are likely present, they are not visible on the BSE image because 1)
exsolution of orthopyroxene in augite occurs on {100} and 2) the lamellae occur on a
sub-micron scale and are too fine to be resolved at low magnification (in contrast to
augite from the other samples). c. Ca Kα X-ray image. Intensity of Ca Kα radiation is
relatively uniform throughout the grain, but patchy zoning is present within the interior.
d. Mg Kα X-ray image. Intensity of Mg Kα radiation varies strongly across the grain.
Intensity is uniformly elevated along the rim of the grain adjacent to olivine and is locally
elevated along the rim adjacent to grunerite. Intensity is also elevated within the interior
of the grain adjacent to larger inclusions of quartz but is depressed in other parts of the
interior.