Bubbles in Thin Section
Sometimes, poorly made thin sections contain bubbles in the epoxy used to glue the rock to the glass slide. Here are two examples.
Talc with Tremolite in a Schist
This is a talc-tremolite schist. The tremolite is clear
in PP light and has 2nd order interference
colors in the PP view. The talc, which
has a dingy green color in the PP view
shows extremely high order interference
colors -- almost "pearl white," in the XP view.
The field of view of these photos is about 2.5 mm. This thin
section was poorly made. Many small bubbles were trapped in the
epoxy when it was prepared. They appear as small round circles
in these pictures.
Epidote in a Basalt
The photos above show epidote that has filled an amygdule in a highly altered basalt. Note several bubbles introduced when the thin section was made. The color of the epidote is typical: a sort of off-color yellow-green. The interference colors, too, are classic: various shades of pastels within individual grains. The opaque material around the amygdule is a mixture of glass, hematite and chlorite.
The field of view is about 3.5 mm. This
specimen comes from Keweenaw County, Michigan