Mike Bandli sent me this antique thin section in 2013. The glass slide is three inches long and one inch wide.
Mike had the slide for a while and back in 2008 he had tried, unsuccessfully, to determine who had made it. He is fairly certain that, given the style of the label, it was prepared in England.
The sample is one centimeter wide and is covered by glass.
In transmitted white light on a scanner.
Closer in plane polarized light, PPL, we see opaque minerals and a few holes in the sample, presumably left by grains that were unintentionally lost, “plucked”, when the section was being made.
The sample in incident light, also called reflected light, shows brown staining and white metal.
At this scale and in cross-polarized light, XPL, those features get lost in the jumble of detail in this LL6 stone.
In closer to the sample and back to PPL we see a round pattern of opaques on the right, the remains of a chondrule.
In incident light we see metal and other opaques in the chondrule rim.
In XPL two barred chondrule fragments stand out.
The brightly colored fragment is 1.9 mm long. XPL.
The brown barred chondrule is 1.6 mm tall. XPL.
Shock induced undulatory extinction is apparent in much of this thin section. Below, see how it appears in this orange, larger mineral grain. XPL.
As crossed polarizing filters are rotated in unison, the matchstick-like grain dims first just below the “head.” The whole shaft goes to extinction before the head does. When the head is in full extinction the shaft has brightened. Finally, the feature is almost back to full brightness when the filters have been rotated almost 90 degrees.
