is topaz different than quartz?
Yes, topaz and quartz are very different. Unfortunately in the
jewelry world, gemstone misnomers abound and "smoky topaz" is one
that's been around for a good while. But here are some fundamental
differences between topaz and quartz:
Quartz is silicon dioxide, or SiO2 and forms in the trigonal crystal
system, while topaz is Al2(F,OH)2SiO4 and forms in the orthorhombic
system. Topaz is also harder than quartz at 8 (quartz is 7) but it
has a perfect basal cleavage and can break along it very easily,
making quartz a bit tougher. The optic character of topaz is biaxial
positive, but quartz' is uniaxial positive. I could go on and on with
refractive indexes, specific gravities and the rest of the
characteristics gemologists use to identify them, but I'm not sure it
would help you and I'm fairly sure you don't have the equipment to
take the readings. But, even with formal gemological training, anyone
can make a mistake, or be fooled.
does anyone recommend a simple layman's book for the
composition of stones? i just read on the archives that
"Chalcedony, a cryptocrystalline quartz, has many varieties
including agate, onyx, carnelian, chrysoprase . . ." i'd like to
know more like this.
I don't know of a mineral composition book that was written in
layman's terms, but a lot of people start out with Rocks, Minerals
and Gemstones, by Walter Schumann. I can recommend something even
better, though: The Internet. One really great link about gem and
mineral composition is:
http://webmineral.com/crystall.shtml The Crystallography link and
the Determinative Mineralogy links can help you lots, as can many of
the others there.
To learn about gemology and gem identification, one of the best
sites around is www.yourgemologist.com Every facet of gemology and
gem ID can be found there, from gemstone characteristics to the
equipment used to ID them. Just wait until you realize just how much
of the material we use as gemstones is basically SiO2!!!
i also found on a website that all their garnet beads of the
purply/red color were dyed. is that always the case with that color
garnet? and what color was it before?
No, that isn't always the case, and it seldom is with any species or
variety of garnet. However, I have read here on Orchid of dyed
garnets that lose their color simply by a soak in water. I've never
seen a garnet do that, though, so I've no idea what color they would
have been before. Hopefully, someone else here will know.
I realize that I've suggested some courses of exploration that may
be more academic than you'd like (gemology can be boring to many),
but it really does take some research to gain the knowledge you need
to make good buying decisions in the world of gemstones and jewelry.
To help you best with the quartz/smoky topaz problem, I'd say your
best first step would be to seek out and learn as many of the most
common gemstone misnomers you can, and learn what they really are.
Here are a few examples:
smoky quartz: smoky topaz, burnt topaz, Scotch topaz pyrope garnet:
Colorado ruby, Cape ruby, Arizona ruby spinel: Balas ruby, spinel
ruby, almandine spinel, sapphire spinel, sapphirine dyed black
chalcedony: black onyx (yeah, it's almost always dyed) calcite: onyx,
Anyway, I'm sure you can begin to see how confusing it can get.
You'll find that practically every gemstone has at least one
misnomer that can confuse you. Get to know them, and you'll be much
more difficult to fool. GIA's Gem Reference Guide is not cheap by
any means, and it isn't in layman's writing, but it lists all the
characteristics of common gem materials (and some uncommon ones),
including most misnomers. It also includes typical enhancements such
as heat, irradiation, dye, polymer impregnation, etc., and the
typical methods of those enhancements.
I'm sorry, Jocelyn, that I couldn't simply list a book that has a
quick, easy system of gem properties in layman's terms, but the
reality of the gem world is based in scientific study, even if that
study consists of years in the business, looking at them every day
as opposed to years in the classroom, reading books and taking
equipment measurements and peering through microscopes. But, I do
hope somebody here has one to offer, because I'll probably be the
first to order one!!!
James in SoFl