This clast
has a glassy rim on the left and top (with a glassy
spherule?). Glass is isotropic so it is
transparent in plane polarized
transmitted light and black in cross polarized transmitted light. It appears dark, here, in reflected
light. Each frame is 1.5 mm square.
This
metal is almost certainly of meteoritic origin. Reflected
light. Field of view is 1.4 mm wide.