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Wood agate Vs. petrified wood


#1

Here’s a question for you folks who’ve studied the nomenclature of

Is “wood agate” the same thing as petrified wood or is it an agate
that just looks like wood?

I’m working on a small glossary type thing for the gemstones that we
offer, and am having some problems finding definitive facts -
considering many of the beads are sold by common names rather than
scientific ones. (That’s another story.) I sure wish there was
some wonderful web site that had a comprehensive compendium of all
the although I’ve found quite a few good sites that cover
most of them.

Any help on this one would certainly be appreciated.

Thanks in advance.
Susan
Sun Country Gems
www.suncountrygems.com


#2

Hi Susan.

I would presume that “wood agate” refers to petrified wood.

Most petrified wood has been buried under volcanic ash or in mud and
bogs where dissolved silica and minerals saturated the wood and
eventually crystallized within the cell structure.

I believe that the most common replacement is agate though there are
some other possibilities. I have seen petrified wood pieces with
agate and crystals of quartz or amethyst lining cavities and on the
outside surface. Some specimens may include areas of calcite and
calcite crystals.

My experience has mostly involved these replacements though I’m
certain there are other minerals as well.

HTH
Pam Chott
Song of the Phoenix


#3

Susan, There are many Rockhound sites online, and one specifically
for Petrified Wood. Please check out Yahoo Groups, as well as Bob’s
Rock Shop.

Petrified Wood is mineral replacement of the cells of wood. Wood
agate is a new one on me. Teresa


#4

Susan, I agree with others that there is petrified wood and there is
petrified wood! However, having said that, I have looked and cut a
lot of pet wood and find all sorts of anomolies out there. You know
we have agate, jasper and what I call jagate or agjasp…you know…a
mixture of clearly banded agate with opaque areas of true jasper (or
visa versa). Sometimes we even encounter chaljagate where there is
some beautiful chalcedony mixed in!

Well, there is no reason why some person couldn’t further define
petrified wood into the more common jasperized petrified wood and
wood displaying material that looks more like banded agate. I think
it would be rare but it could happen. In any event, anyone who does
so should use it purely for differentiation…not commercial
purposes…unless they have found something so unique that they can
really separate it from the common stuff.

Comments anyone?

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut2


#5

We could certainly fine-tune the language where petrified wood is
concerned. What we are really talking about is pseudomorphs after
wood- with what is commonly referred to as petrified wood, the
original wood was covered with volcanic ash or other silica-rich
material and the wood was replaced slowly by silica as the wood
decayed, with the result that the patterns of the wood, the grain
and in some cases the cell pattern, were preserved in the resulting
pseudomorph. In other cases, the wood was buried in hot volcanic ash
or lava, and the result was that the wood burned out, but left a
cavity in the shape of the limb or twig, which later filled in with
silica. In these latter cases, you have the shape of the wood
preserved, but not the pattern. Most folks call this stuff a “limb
cast,” which, since it is a little like Mother natures investment
casting, is not a bad term. Additionally, the silica which replaced
the wood (or filled the cavity left by the wood) can be either
cryptocrystalline quartz or opal. So really, we have four different
stones falling under the general category of silicated wood
replacements- agatized wood, opalized wood, and agate and opal limb
casts. If you wish to consider chalcedony wood replacements as yet
another separate category, things become more complicated.

Lee Einer