[Rockhounds] heat treating for color

[Tim Fisher]

At 06:40 AM 10/30/2007, you wrote:
>
>In a message dated 10/30/2007 5:28:03 AM Mountain Daylight Time,
>nospam at orerockon.com writes:
>
>http://orerockon.com/Heat_treating.htm
>
>
>I was just looking at that page of your site, Tim.  For those of us  "not
>into" this, I was quite surprised at all these recipes for heat-treating
>jaspers, etc.
>
>Does anyone know if Native Americans did any such heat-treatment of jaspers
>and flints before knapping them, or did they just use them "as is"?
>
Yes they did. Agates and jaspers are not knappable as-is. The 
paleoindians actually mined agate and jasper by building large fires 
against the outcrops and allowing flakes to spall off from the heat 
(they probably quenched the material with water to help speed the 
process along). This also tempers the material for knapping. I have 
been in two caves at the Polkadot agate mine in Ashwood (central OR) 
that were made by native Americans over hundreds (if not thousands) 
of years with fire. They mined thousands of pounds of the agate from 
these caves. I have Polkadot bifaces and points from as far away as 
the Malheur Cave in SE OR.

>A separate question, from improving the "knappability" of stones, is about
>its improvement of their color.  How do people feel about the ethics of of
>"improving" color in stones by heat treating?  I don't know a whole 
>lot  about
>such things; for example, I had no idea that some carnelian is 
>heat  treated to
>improve its color.  To a degree, I tend to feel that such  treatment 
>is, well,
>should I call it dishonest?  Although we all know that  this is commonly done
>in many various way, for many materials.  These  treatments make them look
>pretty for sale in gift shops and use in jewelry, but  of course we 
>collectors,
>hope we know when we are buying material, whether it is  "natural" or treated
>or enhanced in some way.  I don't expect to see things  labeled about that in
>a common gift shop, but one would hope that they are  so labelled if 
>they have
>been treated in ANY way, when sold to collectors!
>
Carnelian is almost always heat treated, Pete. Ditto for Brazilian 
agate nodules. Sorry to burst your bubble.

>P.S., in scanning the list on your site, I was a little bit
>(shocked/concerned?) when I saw a recipe for heating "mook jasper" 
>on the  list.  I have a
>really nice piece of "mookaite", and it's one that I  particularly 
>enjoy showing
>to kids when I'm giving presentations to school  classes about 
>rocks; they are
>always impressed with the beautiful color pattern  of bright red, yellow,
>buff, tan, plus the cute name.  I'd be very  disillusioned to know that these
>beautiful colors have been enhanced by heating;  I've always assumed 
>that my rock
>is completely natural (and I still hope it  is... but now I'm not completely
>sure).
>
The recipe is to make it knappable. I doubt it improves the color 
much if at all.

>Pete

Tim Fisher
Ore-ROCK-On!
Email address at http://OreRockOn.com