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