a few images of rocks under the microscope

Quartz grains:
(blue color is epoxy)
Dolomitic silty shale:
different size particles
Microcline (K-feldspar):
a characteristic pattern
Siltstone:
under natural light
Siltstone:
under crossed polarizers
A red algae:
calcium carbonate
Cellular structure of a marine (benthic) organism:
calcium carbonate
all photos Sandstone Petrology CD, 2007