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:
The following example shows the subjective effect of having the same "mineral" surrounded by a "mineral" of a different color.
Other References to Reflectivity and "Color"
An Atlas of Opaque and Ore Minerals and their Associations from the SME
Reflected-light Microscopy from the University of Utah.
Data from the "Visible Light Spectrum" program from efg's Computer Lab was used to obtain the spectral colors used in the calculation of the macroscopic color based on reflectance measurements.
Dan Bruton's COLOR SCIENCE web page.
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