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Andalusite
This gem is named after Andalusia, where fine
crystals occur.
Appearance It is a dull yellowish green with
faint pink or brown reflections, or it may be yellowish brown-green
or even violet brown-green or, rarely, a definite green. The
difficulty in describing the color of this gem is because
of its strong pleochroism, which is heightened by the facets
of cut stones, to the point of being almost iridescent; but
the colors are never very lively. It has unexceptional, vitreous
luster. It is regularly given a faceted, mixed oval cut; square
or rectangular step cuts are also used, but these are less
suited to its modest luster and cannot do justice to its exceptional
pleochroism.
Distinctive features Its peculiar
color range, unusual pleochroism, and modest luster make it
quite easy to distinguish from all other gems. Some say it
can be confused with alexandrite, but the pleochroism of andalusite
is very different from the true color change of the other.
It is true that when alexandrite is a yellowish green with
a faint color change, it may look vaguely similar; but checking
the density would immediately distinguish between the two
stones. The chiastolite variety with its black cross-shape
is unmistakable.
Occurrence The gem variety
comes mainly from Brazil (state of Minas Gerais), but also
Sri Lanka, Burma, the Soviet Union, the United States and,
of course, Andalusia.
Value Quite low, probably because
of the rather drab color and poor luster. It is anything but
a rare stone, yet it is not plentiful on the market and is
mainly in demand with collectors. The most valuable stones
are those with the most pronounced greenish to reddish pleochroism.
The chiastolite variety has a longer history of gem use than
the transparent type, having been worn as an amulet, but its
value is equally low and similar to that of opaque ornamental
materials.
Simulants and synthetics Not
being valuable or well known, it is not imitated. Nor has
it been produced synthetically, at any rate on a commercial
scale.
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