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This list digest contains the following message subjects:

1. LapDigest News for Issue No. 192 - Tues 1/5/99
2. NEW: Polishing Jasper in a Vibratory Tumbler
3. Re: Questions about an Opalized Clam
4. Re: Questions about an Opalized Clam
5. Re: Questions about an Opalized Clam
6. Re: Questions about an Opalized Clam
7. RE: Questions about an Opalized Clam
8. RE: Questions about an Opalized Clam
9. RE: Which Oil to Use in a Slab Saw?
10. RE: Which Oil to Use in a Slab Saw?
11. Re: Variscite
12. BIO: Sarah Holstein
13. BIO: Robert M.B. deJager
14. BIO: Don and Kay Vail


Subject: LapDigest News for Issue No. 192 - Tues 1/5/99

Thanks to all who sent their URLs and brief descriptions of
your web pages; I will try to get these added sometimes in
the next 6 weeks or so. In the meantime, a new show will
be mounted and should be up in a couple of weeks.

Take care of yourselves and have fun! Life isn't a trial
run -- it's the real thing, so have fun now!!


Subject: NEW: Polishing Jasper in a Vibratory Tumbler

I know this sounds dumb...but I'm an opal expert and don't
know a thing about semi precious stones like Jasper and
chalcedony . I've got a bunch of jasper offcuts I want to
shine up in a vibrator for some aboriginal friends of mine.

I've put them through 320, 400, and 600 grit carborundum.
They are now a nice smooth mat finish but I thought I might
ask someone before going to 1000 grit..or cerium oxide....

Can anyone give me some counsel on the subject?

Thanks so much,....

Peter Brusaschi

Subject: Re: Questions about an Opalized Clam


There is generally a lot of potch around the clam. Most of
the shells or pieces of shell will have a highly crystal
structure. Lots of red and green very little blue or
purple. Sometimes there is no color visible at all until
you get down past the potch covering the opal, sometimes the
later of opal will be real thin sometimes it will be
throughout the whole shell.

My suggestion is you run it through a vibratory tumbler for
a few minutes watching it very closely. I look every 15
minutes and I do not start with coarse but with a medium
grit. You can them see if the fire is all the way through
the piece. I gets lots of pieces and lots of whole clam
shells and partially complete more than just a piece.

I think you will find the brightest opals are generally ones
that replace living material. Look at the fossilized wood
and various other pieces and you will see very bright


Tim Vogle Enterprises
P.O. Box 421
Redan, Ga. 30074

Subject: Re: Questions about an Opalized Clam

About the opalized clam, I'd keep it as the somewhat rare
specimen it is and cut something else. Hey I bet you could
trade it for even better opal rough that it more than
likely is.

Ken Wetz in Venice Florida
98 ST1100 "KenS Toy"
STOC 793

Subject: Re: Questions about an Opalized Clam

The very last thing I would do is cut that clam in half. If
you cannot possibly live with it as a fossil, I would gently
grind off the outside of the "shell" if you start to see
color slow down, These types of opal are usually very bright
and very high quality. Take off as much of the white outside
of the clam as you can without actually cutting into the
color then evaluate what you have. It is possible that you
will only find color in a small area of the shell or maybe
if you are lucky the whole thing will be color. If this was
mine I would not cut it but it is yours so do what you want
but go slow and careful so you don't wind up with a pan full
of rock dust.


Subject: Re: Questions about an Opalized Clam


I have an opalized Clam Shells also.

Most of the Opal Shell Fossils come from Australia.

The fire usually runs in bands like the material from
Spencer, Idaho.

If it is a Solid piece of Precious Opal it shows, especially
when wet, try Glycerin or a light oil, and look the stone
over under a bright light you should see the fire area(s)
look for bands that are a different color than the rest
then check them.

The Shell that I have the fire runs up and down through the
shell, not across the shell in line with the hinge. If yours
does the same cutting it across the hinge area would cost
you most anything you were trying to achieve, unless you
like REALLY small stones.

Personally if it has fire in it and you want to polish it
try polishing the entire shell, it would make a nice
conversation piece just be careful cutting the shell, you
might not get what you want and at the same time ruin a
good fossil.

Gil Shea

Subject: RE: Questions about an Opalized Clam

I've purchased opalized bivalves in the past, and although
the shells of some were replaced by precious opal (with
fire) the centers were replaced with hardened mud. This may
not be the case with all opalized clams, but I suspect it
holds true for the majority of them. Since the opal was not
the very best for cutting, nor was it in a very auspicious
configuration, I felt that the pieces were much more
valuable as fossil specimens than as cut stones.

If it's possible to polish just the edge, where the fire
appears, without grinding away too much of the shell
texture, you might get a piece that has both fire and
texture, which is probably the best you can expect. If the
fire continues through the entire exterior of the shell,
then brush polishing with Zam might bring out the fire
without wiping out the texture- but be careful not to let
heat build up.

Andrew Werby

Andrew Werby - United Artworks
Sculpture, Jewelry, and Other Art Stuff

Subject: RE: Questions about an Opalized Clam

Do you cut it or not? My answer to that question(s) is: If
you like to keep a specimen of an opalized clamshell, keep
it intact, or obtain another, then cut away.

I had a piece of an opalized clamshell that plagued me for
several years. I cut it, and it had a zigzag line of brown
running right across the face. The fire was very good, but
the line annoyed me. Finally I got more courage mustered up
and went at it again. This time I got through the brown seam
line (where the two halves of the shell met) and the fire
opened up to the best fire I've ever cut. A #4 out 5 on the
Downing scale. The stone was 5 carats, and a killer.

Yes good fire can exist from opalized clamshell. Now the
question I have: Was the good fire from an interior area of
replacement or from the clamshell itself? It was a very
large almost single sheet of fire, not too dissimilar from
mother of pearl. Well that particular stone vanished with
a box full of treasures to a thief who apparently wanted it
more than I did.

Mark Greenbaum
M.G. Designs - Custom Handmade Jewelry, and Gemstones.

Subject: RE: Which Oil to Use in a Slab Saw?

At one time there was a dielectric liquid called PCB
(polychlorinated biphenyl) used in the electric utility
industry. Over time due to maintenance and such the PCB and
regular transformer oils were mixed contaminating the
transformer oil. . By Law anything over 500 parts per
million of PCB contamination is considered the same as 100%
PCB. Most new equipment has zero parts per million now, and
I suspect there is very little out in the field with over
50 parts per million now. Which is still considered by some
to be a dangerous amount of contamination. The government
says 50 ppm is safe, however I'd err on the safe side and
avoid any detectable PCB’s.. I use TX oil in my saws, it's
just high grade mineral oil. But I know where my oil comes
from and that it contains no detectable levels of PCB.

Just thought I'd flesh out where this not using TX oil
comes from.

Ken Wetz in Venice Florida
98 ST1100 "KenS Toy"
STOC 793

Subject: RE: Which Oil to Use in a Slab Saw?

I have found the best all around oil for slab saws is "deep
well " oil. That is nothing more than commercial mineral
oil. Runs cool. No smell. Don't need a lot of ventilation.
Don't taste bad when, (not if), you get it in your mouth,
does not thicken with cold weather, washes off real easily,
(with dish soap), and best of all, it is not expensive. You
can get it at most bulk oil dealers for about $3 to $4 per

Hope this helps some.

Roy Freeman
Bakersfield, Ca

Subject: Re: Variscite

Just to inform you-all that variscite has been found in
simple and complex crystals and radiating spheres with
crystal points from Willis Mountain, Buckingham County,
Virginia. This mountain is being mined for kyanite from an
impure quartzite by Kyanite Mining Company owned by a Mr.
Gene Dixon. The variscite is found in a sometimes green
fluorescing quartz vein (SW) in association with green
apatite (orange SW), yellow lazurite (the first reported
occurrence of the previously theoretical iron-free end
member), trolleite, topaz (blue white SW), and gyozite
(variable cream SW & LW). Other minerals are found in
the quartz vein that have not yet been identified. Kyanite
near the vein will fluoresce blue (SW) or peach (LW) and
red (SW). Pyrite and rutile are common accessories in the
quartzite and fuschite (a chromian mica) is occasionally
found. Altogether, this quartz vein is a neat mineral
occurrence which I have traced along the ridge of Willis Mt.

Of interest to you may be the 12 ct. trolleite cab that I
had the late Bill Baltzly (owner of the Morefield Mine) cut.
I donated this gem to the Smithsonian Museum in DC. It is
not on display but you can ask to see it during week-day
hours. Trolleite was found first in Sweden as a blue, vein
filling mixture with clay [clay mixture- similar to
turquoise- note that crystalline turquoise was first found
in Lynch Station, Virginia], similarly in the Mono Mts. in
California, as yellow crystals from a pegmatite in Rawanda,
and most recently in Virginia found by Bill Giannini, a
geologist now retired from the Virginia Division of Mineral
Resources. Trolleite from the Virginia occurrence is a milky
light apple green with some indication that clear facetable
material may yet be found, [similar in appearance to a milky
beryl]. Trolleite has a hardness of 8 1/2 thus satisfying
the requirements of durability, pleasing appearance, and
rarity. A new gem material has been "born".

Lance Kearns of James Madison University in Harisonburg, VA,
has my donated reference collection of this material if any
of you should be in his neighborhood. I am also donating to
the Smithsonian a similar reference collection. Fred Parker
of Columbia, MD may still have some of these materials for


Subject: BIO: Sarah Holstein

I am new to this list. A little bit about myself is that I
more or less recently (if you count a year recent) joined
the Central Carolina Gem and Mineral club. Thanks to my good
friend Geoff Haughton for showing me this mailing list, and
for producing pretty much my entire collection of specimens.

I am hoping that I can find some new or used equipment. I am
looking for a used Cab-Mate, such as the one Mr. Haughton
possesses. Also, my father is interested in a good rock
tumbler. Thank you.

-Sarah Holstein

Subject: BIO: Robert M.B. deJager

Hello everyone,

I subscribed to the list in other to get in touch with
fellow agate collectors. I just like to cut and polish them
and find out how they originate and scan them for my
digital archive.

I'm a father of two kids and I'm living in the north part
of Holland(flat) and we visit Idar-Oberstein two or three
times each year and collect rough agates and jaspers.

Anyone who would like to know about German agates and may
be interested in swapping them, don't hesitate to contact

Some of my agate-pictures were put on the Internet at Roger
Pabian's web site :


listed under Germany.


Subject: BIO: Don and Kay Vail

I come by the name "Sailor" from many years of sailing off
the SoCal shores in our family boat. The boat is gone but
the name lingers on. Now we sail about the country in our
car and trailer, my wife of several decades usually in tow,
if not leading.

We decided to become involved in rockhounding and lapidary
as it fits so well our interests in the out doors,
exploration, adventure, etc. I used to do lapidary work when
I was in the scouting "Explorer" program (Post 291 at
Fullerton, for those of you who may know) many years ago
but have forgotten more than I knew.

I start my first lapidary class tomorrow night through
Citrus CC (I hope) and we are both looking forward to many
hours of good fun and friends.

Don and Kay Vail
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