I have a cousin here with a ranch in the Columbia river basalt
flows. Much of the material he finds on his place has chalcedony on
the outside and opal towards the core…whether common opal and
chalcedony or petrified wood. He has a theory that the opal
eventually becomes chalcedony under our hot, dry conditions in the
summer. But I have never heard a professional state such a theory.
Rose Alene, central Idaho
Okay,
“Agate, as opposed to Chalcedony”
Agate is Chalcedony and so is Jasper. We just don’t call certain
types of Chalcedony “Agate” or “Jasper”
If a Chalcedony is opaque, we call it Jasper. If it is translucent,
we Might call it Agate, unless it is Colorless, Gray, or White.
Sometimes if its Blue or Purple we call it Agate. Sometimes if it’s
Blue or Purple we call it Chalcedony. But you cannot say that Agate
is different than Chalcedony. It’s the same thing.
You would do well to make agate burnishers out of solid gray
chalcedony, like the chalcedony found lining High Quality Brazilian
Amethyst Geodes. In fact, I couldn’t think of a better use for that
material.
For the sake of this discussion it is wise to stick with material
that is eye clean. Banding should not matter in all cases. It depends
on the integrity of the layering. You could use True Onyx, as opposed
to Calcite Onyx (which isn’t Onyx at all!) and have no problems. You
could also use a nice Solid Jasper too.
I haven’t made agate burnishers, but I’ve though about it for 16
years. For me, it’s a toss up between the Chalcedony from a Brazilian
Amethyst Geode and Carnelian.
TL Goodwin
Lapidary/Metalsmith
http://thepacifikimagestore.com
She describes a guy in Australia growing opals in jars. He claims to discover some process.
So far as I know (which is somewhat sketchy at best on this) the
Gilson synthetic opals are not much different. The process involves
producing silica gel in micro spherule form suspended in water, and
simply letting the emulsion settle out and dehydrate until it’s
solidified enough to handle, or some such. The bit about opal being
micro spherules of silica gel, however, can be verified. Electron
microscope images of opal clearly show that structure. Beyond that,
how and where it can form, and how long it might take, is perhaps
anyone’s guess. But if Gilson can get it to form in a lab in a
reasonable amount of time, then I’d guess it forming in the hollows
of bamboo wouldn’t be out of the question, so long as there is some
initial source of the silica…
Peter
You stated the generally accepted theory and most gemologist agree with it, but than there are things like opals forming inside bamboo.
I read an extensive article a few years ago, I think in Smithsonian
Magazine, about oddball gems like conch pearls (which are rare but
real) and bamboo opal. If I recall correctly, no one has been able
to definitively prove it (you can’t prove a negative), but the
evidence seems to support the conclusion that the bamboo opal does
not actually exist, that it is a hoax to fool the tourists. I do seem
to recall that the author could not say for sure either way.
Noel
(which is somewhat sketchy at best on this) the Gilson synthetic opals are not much different. The process involves producing silica gel in micro spherule form suspended in water, and simply letting the emulsion settle out and dehydrate until it's solidified enough to handle,
“Gems Made By Man” Kurt Nassau, One ISBN is 0801967732, chapter 22.
There’s pictures… It’s put on special tables that are absolutely
motionless, and it takes around a year.
but the evidence seems to support the conclusion that the bamboo opal does not actually exist, that it is a hoax to fool the tourists.
This is far, far away from agate burnishers, but no matter. I’d
never heard of Noel’s “bamboo opal” Good ol’ curiosity…Google
“tabashir” or “tabasheer” and you’ll find a bit. Like:
http://www.virtualherbarium.org/grass/bamboo/tabasheer.htm
Of course, it’s not opal, it just a resin that looks like opal - a
nickname.
This discussion prompted me to do a little more research. It seems
like agate burnishers are more useful for gilding rather than
burnishing bezels.
I do like the idea of making a bezel roller out of brass. I say that
after scratching a nice Lapis cab with my steel bezel roller
yesterday…
Rick Copeland
rockymountainwonders.com
One example of agate with layers of opal are the thunder eggs from
Richardsons Ranch in Oregon. There are ones that have layers of
white opal and chalcedony, then there are some with pink opal. I
notice the fellow operatng the bull dozer and picking them for retail
sales there was not even picking up the ones with opal bands. Those
cracked like crazy as they dried out. I did see one that had done its
cracking ages ago and the cracks were all filled with agate. It might
have held together. They didn’t charge me anything for the half
filled “egg” that had lovely pink layers and a sprinkling of druzy
crystals with tiny black crystals on the flat surface. Durn specimens
like that won’t cut and polish!
Incidentally, rockhounds can no longer camp at Richardsons. There
has been no charge camping there for years…but someone cut down a
big old tree just to have firewood one night last summer…and that
was the last straw.
Rose Alene
There’s been all this talk about is it opal, is it cryptocrystaline,
should you avoid fortifications, etc., but nothing about HOW TO DO
IT. Tom & Kay Benham wrote an article about how to do it. I’ve made a
few myself from banded agates and blue lace agates. They work just
fine. (Maybe i’m not a demanding burnisher…). For those interested
in how to make your own, here’s the link:
disclaimer: yes, I’m a fan of Tom & Kay. Great teachers, wonderful
articles, just all-around nice & knowledgeable people. Fellow FSG
members.
best regards,
Kelley Dragon
Member, Florida Society of Goldsmiths
I do like the idea of making a bezel roller out of brass. I say that after scratching a nice Lapis cab with my steel bezel roller yesterday...
Make a bezel roller out of stainless.
I'd guess it forming in the hollows of bamboo wouldn't be out of the question, so long as there is some initial source of the silica..."
Interestingly, bamboo does have silica held within it, which is why
you can use a bamboo stick to polish metal without charging it with
any compound. However, I have had organic and colloidal silica
explained to me before but have never properly understood it, much
less the mechanism by which it turns from liquid into something
useful like a piece of flint or an opal.
CP
Cooksons in the UK have Agate burnishers and the description and use
is at
I have also seen hematite burnishers available in the UK as well
Robin Key
Clavis Jewellery
Aberdeen, Scotland
I searched for “agate burnisher” in Google Shopping and came up with
quite a few hits for agate burnishers you can buy. Also, as mentioned
previously, Tom & Kay Benham wrote an article about agate burnishers.
The article was published by Lapidary Journal (before their name
change) in the Jul 2002 issue. There is also a step-by-step article
about making them in the same issue. If you don’t have that issue or
can’t get your hands on it, the step-by-step article is available for
$4.00 USD at
Mike DeBurgh, GJG
Alliance, OH