I've been avidly reading these recent posts about opals on Orchid.
Please, if you have the time, can you direct me to any online sites
or books that may help me understand a little bit more about
Mexican fire opals.
I don’t wish to bore anyone but first let’s discuss the definition
of “Fire Opal.” Fire Opal is red, orange or yellow opal, generally
without play of color. It was so named because its body color
reminded people of flames.
Opal with play of color should be called Precious Opal although for
years it has popularly been called fire opal. Very confusing. Orange
opals from Mexico with play of color are sometimes called Precious
Orange Crystal Opal so the terminology is difficult. I own a pair
that are mind-bogglingly bright and colorful. Fire opals (without
play of color) come not only from Mexico, the most famous, but from
places like Nevada, Idaho, Oregon, Brazil, Tanzania, Australia and
If you’re looking for an inexpensive but comprehensive book about
opal buy Fred Ward’s Gem Series volume “Opals.” It has a chapter
devoted entirely to Mexican Fire Opals. If you want a real opal
education pony up the $40 or $50 for the new Lithographie, LLC book
"Opal: the Phenomenal Gemstone." Excellent! (ISBN 978-0-9790998-0-9)
Mexican precious opal with play of color that’s cut as part of its
native buff or orangy rhyolite matrix is known as "Cantera Opal."
Cantera means “quarry,” and such stones come from quarries at
Magdalena, Queretaro and possibly other Mexican locations. Removing
such opals from their matrix can easily break them so they are cut
together as one stone.
BewaRe: I noticed a lot of phony Canteras with man-made opal for
sale to tourists on a cruise to the Mexican Riviera a few years ago.
Some natural Cantera opals can be very beautiful: I own a natural
black Cantera opal I wouldn’t part with (well, make me an offer I
can’t refuse). Many colored gems (not just opals) sold at high-volume
tourist locations in Mexico are synthetics or simulants. I noticed
lots of synthetic amethyst and “reconstituted” lapis, turquoise,
malachite/chrysocolla, etc. for sale.
Buyers should be aware that a new synthetic fire opal marketed as
"MexiFire" is currently being sold, as is a synthetic Peruvian blue
opal called “PeruBlu.” I’m not sure why anyone would bother since
natural stones are fairly abundant and reasonably priced but a Thai
company has. Details heRe: http://tinyurl.com/bdops7