In the course of looking for interesting gems to set in my
jewelry pieces, I've run across Andalucite. I'm not that familiar
with it, but it is very pretty, with interesting color and clarity.
Hi Karen I get the feeling that some people (as I have on occasion
done) confuse Andalusite with Alexandrite. Vaguely similar names,
both of the orthorhombic crystal systems and both with their own
My reference here is a little book called “Gemstones” by Cally Hall
(a handy book with great photos and pretty accurate in its info I’m
told) and I quote: “Andalusite varies in colour from a pale yellowish
brown to a dark bottle-green, dark brown, or the most popular
greenish red. It has very strong and distinctive pleochroism, so
that, when turned, the same stone may appear yellow, green and red.
Large crystals may be vertically striated prisms with a square
cross-section and pyramidal ends, but are rare. More usual are
opaque, rod-like aggregates of crystals or waterworn pebbles. It is
the pebbles that are usually cut as gemstones.” Occurences - “gem
gravels of Sri Lanka and Brazil. Other localities include Spain,
Canada, Russia, Australia and the USA.” Hardness is 7 1/2
There is no mention of rarity apart from that one crystal variety.
Alexandrite (which is a form of Chrysoberyl) on the other hand is
"very rare and valuable" and “changes from green in daylight to red,
mauve or brown under incandescent light, such as a light bulb.
Synthetic chrysoberyl, synthetic corundum and synthetic spinel have
all been produced to imitate alexandrite’s colour change.” In
regards to occurrence it states “although mainly worked out, the
best chrysoberyl, including alexandrite has been found in mica
shists in the Urals (Russia)”
There’s heaps more, but you may see from this the likelihood of
possible confusion amongst your informants.
As to lab-created (synthetic) gemstones versus natural. Beauty is in
the eye of the beholder. Actual brilliance must be the same in both
as they are the same mineral, ie your Alexandrite is a Beryllium
aluminium oxide and so is a synthetic Alexandrite, otherwise it is
not a synthetic but rather an imitation. It is the minute little
bits of other things that that make an alexandrite appear so
different from a crysoberyl cat’s eye (also Beryllium aluminium
oxide). Refractive index is the same for both. Personally, although
sparkly and pretty, the synthetic corundum imitating alexandrite is
not a patch on the real thing. I had the good fortune to see one
once. In natural light it was a deliceous deep blue green and under
incandescent light an intense pinky purple.
All that gasbagging and you were asking about Andalusite. Hope the
above was of some use though.
Renate from Adelaide, South Australia in the north of which state we
find another form of Andalusite, call Chiastolite which are cigar
like prisms which when cut in cross section have a cross-like pattern.