My latest Analysis
My new analysis is based on a number of new insights into the groundmass and texture of the rocks, captured by the rover's cameras.
The photos published so far by NASA allow the conclusion
that the boulders and remnants of it are all
of igneous origin. The boulderss, which are chaotic
deposited on the bottom and in the sandy elevations, are in a strongly varying
stage of their disintegration. "Fresh" boulders are usually angular and have
a dark groundmass. In the stage of disintegration they dissolve columnar
to friable. In the final stage of disintegration, the flat and brighly colored
stones are in the ground, or it are remnants of total crumbled boulders.
A main component of the matrix in the boulders is dark hornblende (amphibole). This explains the many reflections that emanate from the crystal surfaces when light is incident. These reflections were referred before as mysterious "bright inclusions". Another component are obviously bright-colored pyroxes (and olivine), because strong concentrations of magnesium and calcium are detected in a single spectrogram published so far.
The different stages of the disintegration of the
boulders suggest that these were included in the glacier moraine at different
times. The youngest boulders (from the upper parts of the moraine) are still
angular and "fresh". The oldest boulders, which are already in the final
stages of disintegration, come from the lower parts of the eroded moraine.
1.) Composition of groundmass and phenocrysts
Hornblende and Pyroxe in the groundmass
Olivine in the groundmass and as phenocrysts
An exposed rock (Sol-37) is described as puzzling. It has a smooth surface (almost vitreous) on which numerous rounded depressions can be seen. Upon closer inspection of the photo, I notice that some of the depressions still have a brownish (not secondary) filling. Obviously these are the typical remnants of decomposed olivine aggregates, which are already missing in most of the holes.
2.) Stages of disintegration of the boulders
Columnar to friable disintegrated boulders
Boulders in the final stage of disintegration
Boulders with adherent
crust and their disintegrate products ?