This section displays a very distinct breccia texture with many
angular clasts of type 6 chondrite material (ranging in size from some
100 µm olivine clasts to 5 mm lithic clasts) embedded in a finer
grained, darker matrix which appears to be clastic. Three clasts contain
1 to 2 mm sized troilite and metal grains. Many of the lithic clasts contain
large olivine grains which have a polygonized intergranular texture. In
such grains planar fractures have been observed which cross the grain boundaries
of the polygons as if the premetamorphic material had been shocked to at
least S3 (although the present grains have sharp extinction, probably restored
during thermal metamorphism). The clastic nature of the matrix is hard
to confirm by reflected light microscopy alone, it probably needs TEM.
The matrix olivines have a somewhat less transparent appearance (light
tan and somewhat dull) than those of the clasts. They show lots of internal
bright reflections in reflected light at high magnification. At low magnification
the matrix appears simply darker than the clasts. Although most clasts
are rather similar in texture and mode (LL 6 material), some might be xenolithic
such as two dark melt rock clasts (very fine-grained with tiny opaques),
one large troilite grain, one chondrule with spherulitic texture, several
chondrules fragments which have fine-grained crystalline mesostasis and
are therefore akin to type 4 or 5 material, some lithic clasts in which
olivine contains opaque deposits on fractures, and finally some olivine
clasts with planar fractures. Two large clasts contain S1 grains and
grains with planar fractures but sharp extinction (see above). A tentative
interpretation is that this meteorite is a polymict fragmental breccia
in which clasts of variable provenance and variable shock are assembled.
Results
Lithic clasts
| Olivine | 18 | grains | S1 | |
|
3
|
grains | S3 (premetamorphic) | ||
| Total | 21 | grains |
Mineral clasts in matrix
| Olivine |
9
|
grains | S1 | |
|
2
|
grains | S2 | ||
|
3
|
grains | S3 | ||
| Total | 14 | grains |
Whole rock
| Olivine | 27 | grains | S1 | |
|
2
|
grains | S2 | ||
|
3
|
grains | S3 | ||
| Total | 35 | grains |