I have read references to the use of acid to "polish" gem stones
In Mexico all the "onyx" chess sets, small "onyx" carved animals (
man w/ cactus & burro), and other "onyx" trinkets are polished with
acid. This "onyx" occurs in many natural shades of orange, white, &
The real name for this material is massive crystalline calcium
carbonate of which there are several high quality deposits in
The massive calcium carbonate will react vigorously in acid,
removing tool marks and other rough areas, leaving a much smoother
finish. This is the Mexican method used to obtain a quick easy
"polish" on these small cheap items.
Polishing with this method is particular for this type material, and
is based on it's vigorous reaction with acid. There are other
materials i.e. "onyx marbles", "oriental alabaster", in this same
family which will may also be polished by this method.
Hope this helps.
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