Reflected light microscopy is used to examine opaque
minerals (and other materials, e.g.. ceramics) to determine the paragenetic
relationships between different mineral phases and their identification. Often,
the same specimen which is viewed using the light microscope can be analyzed
using advanced x-ray and ion microprobe techniques.
The sample (polished thin section, epoxy grain mount, or polished section) is
placed in the appropriate reflected light microscope. Color is observed using
plane polarized light with the appropriate illumination level.
The sample's color is, at best, fairly characteristic of the particular
mineral. Care must be taken when comparing colors to follow these rules:
Sample is freshly polished and does not have any tarnish.
Illumination level is not too excessive (intensity changes the color
Samples of known minerals are available for comparison.
Plane polarized light provides some indication of anisotropism in
Colors appear to be changed by having other minerals in the field of
The following example shows the subjective effect of having the same
"mineral" surrounded by a "mineral" of a different color.
Yellow Square on Right Appears "Yellower"
Other References to Reflectivity and "Color"
An Atlas of Opaque and Ore Minerals and their Associations from the