Edited and Published by Hale Sweeny
Web Site:
Associate Editors: Geo. Butts, JR Shroeder, Steve Henegar
and Margaret Malm

This list digest contains the following message subjects:

1. LapDigest News for Issue No 257 - Thurs 1/6/2000
2. REVIEW: Feb 2000 issue of Rock & Gem
3. NEW: Quartzite Visit
4. NEW: Coating over Polished Agate
5. RE: Opal Rubs
6. Re: Opal Rubs
7. RE: Opal Rubs
8. Re: Opal Rubs
9. RE: Opal Rubs
10. Re: Source of Warm Water for Wet Grinding?
11. Re: Source of Warm Water for Wet Grinding
12. Re: Source of Warm Water for Wet Grinding?
13. Re: Source of Warm Water for Wet Grinding?
14. RE: Need Sphere or Sphere Maker


Subject: LapDigest News for Issue No 257 - Thurs 1/6/2000

Well!!! New Year's came and went. Nothing happened!!!
What a letdown!! (smile)

I hope each of you has a great 2000! Just remember the
fundamental rule: Enjoy your life! Have fun!


Subject: REVIEW: Feb 2000 issue of Rock & Gem

This month's Rock & Gem contains several items of interest
to the lapidary.

While not directly related to lapidary, Bob Jones has an
article on Quartzsite. Quartzsite is a lapidary heaven
from early January to the middle of February. The warm
winter climate draws rockhounds and RV'ers from all over
the country. Bob also has an article about collecting
around Quartzsite. There are many sites within a couple
of hours drive for both minerals and cutting material.

Another article by James Mulkey describes some of the shows
and treasures to be found.

Sandra Downs brings us an article about collecting in Maine
with the Poland Mining Camp. The Groves host collecting
trips into some of Maine's famous quarries and mines.

James Mulkey's article on Turquoise is an update on the
once again rising popularity of turquoise. The pictures
accompanying the article will make any one interested in
lapidary drool. The article goes into some detail on the
turquoise from The Apache turquoise mine in Nevada.

Cool Canadian Carvings is about Jim Lund of Kamloops, BC.
The articles describes his use of white alabaster for
carving winter scenes. Also described is his carvings of
gold in quartz.

Art and the Lapidary by Lee Martin describes those that
create things from rocks as being artists. Mother Nature
and Father time create beautiful materials for us to work.

Curtis Handy in Rockhounding on a Ranch, describes places
to collect lapidary materials in Oregon's Cascade mountains.
The pictures show some beautiful cutting material from the
area around Madras, Oregon.

Barbara McCondra's article on The Opal of Koroit describes
the boulder opal of the Koroit field in Australia. As
evidenced by the pictures some beautiful gemstones can be
cut from this ironstone and opal combination.

Steve Henegar

Subject: NEW: Quartzite Visit

Any folks going to be out at Quartzite around the 24th to
30th of January ? I will be in Blythe and will be checking
out the shows there and in Quartzite. Oh boy Oh Boy !

I'm going to Silverpick this time. I usually stop every 50
feet out west and haul back piles of leaverites. Hope my
Opal addiction gets well served.


Subject: NEW: Coating over Polished Agate

I heard that you can spray a clear coat over polished agate.
What is the best one to use for this?

Thanks For Your Help

Hi- There are several coatings one may use, including epoxy,
clear acrylic, and so on. But why would you want to coat a
polished agate item. The polished surface is harder than the
coating, and thus can't protect from scratches, etc. If
agate is polished well, you can't beat the shine you get
with a coating, so the question is: why? I wouldn't coat
a polished agate item. I have seen other items, which can't
be polished - such as copper in matrix slabs - coated with
epoxy. hale

Subject: RE: Opal Rubs

The term "RUB", usually applies to Lighting Ridge nobbies
that have been partially worked. IE ground down to the
color. This takes some of the chance out of purchasing
rough opal. Especially the Lighting Ridge material. It can
be very difficult to find the color in the nobbies. What
you get in a Rub is a stone that has the color exposed and
it is pretty much, what you see is what you get.

As to working one, all you need to do is define the shape
and grind down the back, taking care not to remove to much
of the black potch as this is what gives the intense color,
IE don't grind into the crystal opal band. Polish out the
"rubbed" surface and you are finished. In some cases, you
might want to "rub" it a little more but use caution
because as you stated, the color is very thin. NEVER, NEVER
coat them with a coat of epoxy. Save that trick for sea

Don at Campbell Gemstone.

Subject: Re: Opal Rubs

On the subject of rubs. If you get good rubs they should
be prepared just so you can see the line of fire and get an
idea of what is down there. They should show fire all around
the edge of the stone so that you can see how deep the opal
is. I generally do not buy rubs since I can do them myself,
but for the inexperienced opal cutter this is the best way
to go.

Most of the rubs I have seen on my trips to Australia and
over here are good quality and can be cabbed with no
problems. You generally have a return privilege on items
you buy via the mail. I take a careful look at each rub and
if they don't meet what I think they should be then I send
them back.

Just remember the three rules of cutting opal are go slow,
slower still and slower still. You can not hurry a good
stone. Some times If I am cutting real expensive material
($2000 an ounce) I will take a day or better to finish the
stone. I never go more than 2 or 3 seconds without
stopping and looking at the stone.

I hope this helps. IF anyone from the south is going to
Tucson. I will be at the best western at the airport from
the 3rd till the 7th.

Tim Vogle

Subject: RE: Opal Rubs

Hello Hale,

As to rubs: that is a very ambiguous term that applies
mostly to Lightning Ridge opals. Most of the opals mined
in L.R., with promise, are cut directly on the fields (who
can afford to sell a stone for $2000/oz, that when cut, may
be worth $2000-$10,000/ct). So what happens to the stones
that don't qualify as high grade and have the cutting
process already begun They are sold as rubs (Australians
use rubbing synonymously with grinding or to grind on....
.rubs are stones that have been rubbed).

Many of these stones have thin layers of bright crystal
sitting over black or blue potch. Some resemble preforms
and some are merely unfinished semi-rough opal that has
been ground on to see what the heck is inside.

There is a new video book series available (the first
copies were shipped about 1 month ago) by Greg Pardey
(Lightning Ridge opal cutter) on cutting black opal. The
book is titled "Black Opal". The video is well done with
very clear photography. Greg does a nice job of narrating
the cutting process. He takes you through the complete
finishing process and turns a very large nobbie (with
gorgeous blue/green/orange fire....wish I could try cutting
one like that) into several finished cabs that must be
worth upwards of $2000/ct.

The price of the video/book is $99.00. I think that at that
price it is still a bargain. I plan to order 10 copies to
sell, but right now I only have the one copy that was sent
to me with the original shipment. The books can be ordered
through Greg directly or through Peter Bo at Quality Opals
(or through me in about one month). Greg’s E-mail address
is and Peter Bo at Quality Opals is . I am not sure what the price
for shipping was but I think it was $15.00.

I am going to have a complete book revue of this book/video
and of Paul Downing’s new book in my next edition of "The
Opalfield Newsletter" that I send out quarterly (next one
sometime in January). Here is a direct quote, from Greg's
new book, on RUBS:

RUB or RUBDOWN: The general term for grinding opal to see
what is in it, and of course to cut it, hence words like,
rubbing down wheel and 'rubs', the term applied to stones
for sale that have only been roughly rubbed into shape and
are either cut from that stage or are sold as that. The
term probably came from ancient lapidaries who had to
actually rub down by hand

Thanks again Hale and I hope this helps (and I got to be a

Steve and Darlene Newstrom
The Village Smithy Opals
P.O. Box 1334
Billings, MT 59103-1334 USA

Subject: RE: Opal Rubs

Hi Folks,

While I have no experience with the very thin stuff except
in hand grinding paper-thin opal wafers to make up triplets,
I expect a "rub" or very thin layer of opal on matrix will
be amenable to similar treatment as any uneven, baroque opal

One such baroque opal which I just finished for a client
is a piece called "Millennium Bug no.1" It's in sterling
silver and 14 kt gold, and you can see what it looks like
via Keith Rigby's site at

The largest of the three opals is a baroque. I had to grind
down fairly deep to get past the pits. This was done with a
small 100 grit diamond wheel about the diameter of a dime
turning at roughly 900 rpm in a stationary chuck, the stone
being kept constantly moving under the wheel in a crisscross
pattern. Two inches below stood a dish of water into which
the stone was dipped as needed.

The marks from coarse grinding were then smoothed out with
the aid of a hardwood broomstick. I sawed off a 1/4" slice
of the broomstick, put a hole approximately in the middle,
mounted the disc on a finishing nail to serve as shaft,
clamped it in the chuck and turned it, dry, against coarse
sandpaper to center the disk and to slightly crown it. Then
I spun it against some beeswax and then against a hardwood
dowel to heat the beeswax and melt it in. I don't know if
this is necessary. Maybe it's overkill. But that's what I
did. Finally I applied 1,200 grit diamond in Vaseline to the
hardwood wheel, and the wheel to the stone. It did an
excellent job. For the next step I sawed a slit into a
similarly made broomstick wheel and slipped a piece of
2,000 grit wet-or-dry silicon carbide paper into the slit
to hold it against the wheel. You can get this paper from
your local autobody supply shop. Last came polishing with
grease-based 14,000 grit diamond on a hard felt wheel. The
polish came up beautifully clear. In fact, I'm quite taken
with 14,000 grease based diamond on hard felt for agate and
labradorite also. But you need to watch out for heat when
polishing on felt. Also, for an opal rub on porous matrix a
grease based polish might impregnate itself into the matrix
and discolour it. If it's a high value stone you might want
to treat the matrix with waterglass or mucilage to be
dissolved out again later.

Hans Durstling
Moncton, Canada

Subject: RE: Opal Rubs

Hi Hale,
In Australia when a miner looks at a piece of rough opal
and thinks there might be something there he will RUB it on
the grinding wheel. If there is nothing there it will go
into the mine run pile. If on the other hand it has cutting
potential it will go to a cutter. Lots of the lower grade
opal will be rubbed like this and sold to us in the USA as
opal rubs. This is fine in a way because you can see what
you are getting (sort of). But unfortunately many times
they RUB too deep and make it hard or impossible to cut a
nice finished opal from it.

Most black opal is just a very thin layer of color on a
black potch base. If it is finished right you can't tell
how much is color and how much is potch unless you look
very close. Also if it is finished right you won't care how
thick the fire layer is you will be to busy admiring the
colors you can see. If you have a piece of opal with wavy
lines then it is best finished like you would a piece of
Fire Agate. Try to follow the lines of color up and down
and leave the top wavy when you are done. I have seen some
very nice opals cut in this fashion. This is hard to do
especially the polishing phase but the results are worth it.

I hope this answers some of your questions Hale. I want to
take this opportunity to say thank you for making this
online forum possible and to wish you and everyone else a
Happy New Year!

Have a great day,
Michael Sielaff

Subject: Re: Source of Warm Water for Wet Grinding?


I was thinking of trying the bird bath heaters. They are
meant to be under water and are safe. Cold water is a real
draw back to winter stone cutting.

Steve Ramsdell

Subject: Re: Source of Warm Water for Wet Grinding

When our shop was unheated, Keith used a stock tank heater
(purchased at the local Farm Supply and Feed Store). It
wasn't too expensive, had a thermostatic control that kept
it at a proper (drinking water for stock) temperature, and
he could leave it in the bucket overnight, if so desired.

It has already been mentioned that it might not be a good
idea to recirculate the discharge from your grinder.
However, Keith uses a recirculating pump on the grinder
that he makes his marbles on now, and uses the same water
over and over, and it is still running after three or four
years, so it must not be too bad for it. (He was using the
drip method when he was using the heater) It might get
too crowded in the bucket, with the heater and the pump
both in there, but the heater has a float on it that would
keep it at the top, and the pump sits on the bottom, so
they might both fit okay if the bucket is big enough..

Good luck, and Happy New Year.


Keith and Ann Berger
Round Rocks Etc.
Colville, WA 99114
(509) 684-4082
Check our site for GREAT hand made marbles

Subject: Re: Source of Warm Water for Wet Grinding?

Unless all the equipment is hard-wired in, or the breaker
is too weak, what's wrong with an electric hot plate?

Failing an easy electrical source, a two-burner propane
campstove, of which you use only one burner might serve
well. (This to avoid tipping) And you should NEVVA let
the swarf get back into your clean water, so you need three
buckets, one of which should be metal (for heating), one
with clean water to refill as it's used, and one for waste,
which I'm sure everyone is savvy enough to know that while
it is fine for the garden or lawn (sling it, don't pour it),
it's death on sewer pipes!

Ted Robles

Subject: Re: Source of Warm Water for Wet Grinding?

A 220v heater element from a hot water tank will get quite
hot on 110volts. They are inexpensive and come in a variety
of configurations. The main thing to be careful of is the
electric line to the heater element. You will want an
absolutely waterproof connection to the heater, as well as
having the machinery/bucket etc., grounded.

These heaters will also burn out if they are not constantly
submerged. Although running a 220v heater on 110v will
have a significant reduction in this type of burnout, as
the element will not reach it's peak redheat. Make sure
you have the electric wiring idiotproof. Waterproof!!
Even for an unlikely mishap such as overflowing or kicking
the bucket (which is what you will do if you're not
exactingly cautious).

Happy New Year

John g

Subject: RE: Need Sphere or Sphere Maker

Hi Robert! You can find undrilled gem balls on page 222 of
the Rio Grande gems and findings catalog, in pink quartz,
sizes 3mm or 4mm. Nothing in 3.5mm. (1-800-545-6566) A
sphere this small is extremely hard to make by hand, so
thought you might want to consider this option. A marble
that is 2.8" is also in the very-hard-to-make-by-hand

You might also consider banded Brazilian agate for Jupiter.

Good luck on you project,


Ann Berger
Keith and Ann Berger
Round Rocks Etc.
765 E 1st Ave.
Colville, WA 99114
(509) 684-4082
Check our site for GREAT hand made marbles
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