Hardystonite
{Ca2ZnSi2O7}: FL
Blue-Violet SW
Calcite {CaCO3}: FL Red-Orange SW
Willemite {Zn2SiO4}:
FL Green
SW
This is another specimen I found on the Buckwheat night dig
of November 5,
2005.
Hardystonite, calcite, and willemite make a beautiful combination under
the short-wave lamp, as you can see from the photograph. Like
most other fluorescent minerals, hardystonite can have varying
brightness. Some specimens are very bright, while others are
quite dim. Some hardystonite responds weakly under long-wave (LW)
as well as short..
This rock in daylight has a peculiar weathering on one part of the
hardystonite. The franklinite grains have halos around them that
resemble dendrites of some manganese mineral (pyrolusite?), in turn
surrounded by a white coating that appears to be some kind of
alteration of hardystonite. It may in fact be hardystonite that
was simply redeposited as a secondary coating.
The rocks that have this alteration generally have a
certain look to them, right down to the consistency of the calcite and
franklinite.
Note that this is the "back" of the specimen. Below is a
photograph of the same area in short-wave UV:
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