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This list digest contains the following message subjects:

1. LapDigest News for Issue No. 138 - Wed 4/29/98
2. NEW: How to Tumble Fluorite
3. NEW: Drilling Stones
4. NEW: Aluminum Oxide Polishes from FitzCorp
5. RE: A Possible Cheap and Safe Cutting Oil
6. RE: Inclined (Non-Horizontal) Tumblers
7. RE: Using Diamond Abrasives in Tumbling
8. RE: How to Recreate Making Minoan Seals
9. RE: Opal Price Guide
10. RE: Opal Price Guide
11. BIO: Paul H. Miller
12. BIO: Kara C
13. AD: Visit Our Website!
14. FS: Quartz Caps for Doublets/Triplets


Subject: LapDigest News for Issue No. 138 - Wed 4/29/98

My apologies to Leon Kusher, whose address I messed up in
Issue 137. It should be:

Be safe.. Have fun.. See ya on Saturday....


Subject: NEW: How to Tumble Fluorite

Can anyone tell me how to tumble fluorite and end up with a
polished product? I use a vibratory tumbler.

Paul H. Miller

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Subject: NEW: Drilling Stones

Hello All,

I'm wondering what people use to drill holes through stone
such as Lapis, etc. I have a Ryobi (similar to a Dremel) with
some (cheap) diamond burrs but they don't seem to do the
trick. Do I need a diamond drill bit? I've looked around
locally but it seems if these exist I will have to order them
from a specialty shop. My main interest is making necklace
pendants and therefore I need to drill the stone to place a
leather necklace through. I do not want to add any metal to
the piece so wire-wrapping, etc. is out for me for this
project anyway.

Any suggestions are appreciated...thanks in advance.


Subject: NEW: Aluminum Oxide Polishes from FitzCorp

(Ed. Note: This was written as response to the query in #137
about using cornmeal and no water for tumbling. But this item
has not been presented before (at least, I can't remember if
it has), so I am making a new item from it. Hale)

FitzCorp has developed a line of aluminum oxide polishes
that really work good. They recommend using crushed safety
glass as filler in the grinding stages and crushed corn cob
for polishing stage. The glass can be obtained free from most
auto body shops or glass companies. Crushed corn cob can be
ordered from many lapidary dealers, FitzCorp or can be
found at gun shops where hunting supplies are sold.

Detailed information for polishing stones in all types of
tumblers and most other applications can be obtained from:
FitzCorp,Inc., P.O.Box 565, Point Blank Tx. 77364. Phone
1-409-377-2409.. You can also order polishes from them.
They do not have an e-mail address.

I am not affiliated with FitzCorp in any way but have found
their products to be very good. Also they have been a dealer
at our show in Abilene Tx. for several years.

Don, the ramblin rockhound

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Subject: RE: A Possible Cheap and Safe Cutting Oil

<<I think I found one that meets all criteria ...(snip)...
(It) costs about 20-25 cents a >gallon, doesn't wear out
and when it gets weak just add more .. base solution to
what's left after cleaning the sludge (from) the saw sump.
My only thought is that I .. haven't tried it on a larger
slabbing saw yet. Leon []>>

I would be very interested in this new material.

Our Lapidary Club ran about 4 months with Propylene Glycol
antifreeze in an 18" slab saw and found no difference
compared to oil with one exception- the development of
considerable rust on iron parts which were ABOVE the liquid
line, that is, in the vapor phase. This happened whenever
the saw was not in service for two or three days. This saw
has a large hood enclosure.

The club is using PG AntiFreeze in a 10" saw with no problem
at all- going on six months now but the blade lifts from the
base box for storage.

In our own shop, I am using the PG in a horizontal 10" saw
but the fluid is sumped from an external pump box. Likewise,
using PG in our 6" trim saw but it has a plastic insert box
so I pour off the PG when done. BTW, I use Lapcraft's
"Tool-Cool" with the PG, because of the high water content
of the antifreeze.

So, the big slab saw is really where we want to get rid of
the oil but can't because of the rust problem above the
fluid (vise, rails, screw feed bar, etc). If anyone has a

way out of that, we would appreciate any ideas.

I like the cost of the protein solution but it's still
dissolved in water and what to do about rusting... We would
like to hear the test results, when they are ready.

George Butts

"non-commercial republish permission granted"

Subject: RE: Inclined (Non-Horizontal) Tumblers

<<Are there any companies that make rotating (drum) tumblers
that do not have to be covered? Specifically the type that
would be inclined vertically so the tops could be left open
without any cause for spilling the contents...>>

None of which I am aware.

Now, why would you want to do that? For starters, I think
the slurry would dry out and you'd be constantly having to
add water.

I was just musing on this myself a couple of days ago while
dumping my big (12 lb) tumbler. To tumble you must vibrate
or rotate. There are certainly open-topped vibratory
tumblers, but even those usually have lids on them. It seems
to me a rotator must be sealed, even though it IS a bit of a
mess when you open it, hence hard to re-seal if you want to
keep going with the same load.

Alan Silverstein

-- non-commercial republish permission granted --

Subject: RE: Using Diamond Abrasives in Tumbling

<<Can diamond impregnations as in the discs ever be used in
the tumbling process by incorporating them in the drums?>>

Clever idea! But forget it. :-)

My understanding is that tumbling action requires the stones
to move, slide, or roll past each other. Inside a rotating
barrel, the stones "stick" to the inside wall as they are
lifted up to the point where they slide/tumble down the
active face. Larger barrels even have faceted inner walls
to ensure the stones do NOT slide past the walls, as this
could ruin the tumbling action, AND the stones by causing
flats to appear on them.

I saw this happen once in a my little (3 lb), non-faceted
barrel when I tried tumbling a small amount of (soft) barite
nuggets. They didn't make much tumbling noise, and they just
smoothed on one side to match the barrel wall.

Getting the optimal tumbling action is why it's important to
fill the barrel the right amount, 2/3 to 3/4 full. Too
little, and the stones slip or, in a faceted barrel, fall too
violently. Too full, and you don't get a long tumbling face
(and the sound diminishes accordingly). Easily fractured
material still gets beat up in a larger barrel (with a
further drop along the face), which is one reason for using
plastic pellets, sugar solution, etc. to shock absorb.

Science News had a short blurb about the physics of this a
few years ago. In a rotating cylinder full of dry powder or
sand, you don't get as good a mixing action as you'd
like/expect, as one wedge of material after another slides
down the active face. There's a critical fullness that
optimally mixes the material. Fortunately, in a tumbler (I
think) it's less critical because you have fluid and stones
of various sizes and shapes, which might be one reason you do
want to tumble a mix of sizes.

Alan Silverstein
(Ed.Note: It was an interesting concept, but a slightly
different one is whether one might plate - say, stainless
steel or ceramic beads with diamond of various grit size, and
use these instead of SiC for tumbler processing. Would it
work? Would there be any advantage to this? hale)

Subject: RE: How to Recreate Making Minoan Seals

Dear Julie;
You have taken on a really ambitious and interesting project.
If I were you, I would get my hands on "Gem Cutting, A
Lapidary's Manual" by John Sinkankas published by Van Nostrand
Reinhold Company. He has a very thorough chapter on carving
and engraving on page 222. You might enjoy the picture on page
231 of jade grinding equipment used in China. However, on the
practical side, take a good look at the table of raw materials
on pages 224 and 225. You need to choose the softest stone
that the Minoans used. Time is much more of the essence with
you. They spent mega-hours carving the hard stuff like
cryptocrystalline quartz. Best wishes for your success.

Wouldn't it be neat to put your paper in the Lapidary Digest!

Sincerely yours,
Rose Alene McArthur

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Subject: RE: Opal Price Guide

In a message dated 98-04-27 11:32:47 EDT, you write:

<< You can see a $50,000 stone though, and know in your gut
why it's worth that ... the intensity is enough to bring
tears to your eyes and it glows with an inner fire that is
visible across the room!>>

Carol's statement above sums up opal pricing in general. I
have customers come into my store and look at the opal
display and they almost always focus on the most expensive
opal in the display. They generally ask "why does that one
cost so much more than the others?", and my response is that
the stone that talks to you the loudest is the most expensive.
You, as a customer, are buying a thing of beauty and the more
beauty, the higher the cost. This is true for any stone and
most anything else in life.

Don at Campbell Gemstones

Subject: RE: Opal Price Guide

Thanks everyone for your replies about opal pricing.
I'm wondering, since you don't think Paul Downing's opal
pricing book is all that reliable how you feel about his
statement in his other book "Opal Cutting Made Easy" that
"Generally the price per gram is equal to the cost of the cut
stone per carat". Is this a pretty good rule of thumb? Is
this for wholesale or for retail? (the book doesn't

non-commercial copy permission granted

Subject: BIO: Paul H. Miller

I'm retired, and have been since I was 48 (20 years ago).
I've been into lapidary since the early '50s and taught same
at a local community college for a few years. Right now I'm
learning to facet and am enjoying every minute of it,

Paul H. Miller

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Subject: BIO: Kara C

I've been a member of the San Francisco Gem&Mineral Society,
and learning to cab, for less than a year, but I've worked
with gems as beads and in jewelry for several years. One of
my favorite methods is to make beaded bezels around crystals,
large cabs, and interesting, colorful rough or tumbled stones.
I am completely addicted to beads, and hope to make more in
the future (I've made several from silver, and one from a
tourmaline crystal).

I really like stones with interesting inclusions and color
patterning, and various phenomena - as long as I can make
jewelry out of them. Specimen collecting doesn't interest me
- especially since I don't dust! I also don't have much
interest in facetting (of course, I haven't tried it yet) or
facetted stones. I like to combine different stones and
pearls in my jewelry - I rarely design something with just
one type of gem.

I'm currently involved in a challenging project making
wedding rings for a friend that include opal inlaid into
tiny rune (ancient letter) shapes in sterling silver, with a
backing of 18k gold - any advice on this technique and
working with opal would be greatly appreciated, as this
project is a big learning experience for me.


Subject: AD: Visit Our Website!

We would once again like to invite fellow rockhounds to visit
our web site at: We are completely
revising our web site in order to bring you better pictures
as well as the latest in lapidary equipment and supplies. So
be sure and visit often.


Subject: FS: Quartz Caps for Doublets/Triplets

We are owners of one of the Opal mines in Spencer, Idaho. We
want to let you know about something new we are involved in.
We do our own cutting, and most of what we cut are triplets,
due to the thin seams in our opal. We have found it more
difficult over the past to obtain quality crystal caps at
reasonable prices. The quartz caps are a thing of the past,
although some people say the caps they sell are quartz (they
are probably not).

We have decided to use our own manufacturer of the crystal
caps. We have a web site at:

Our prices are VERY competitive starting at .32 for 5mm and
6x4 to .82 for 14x10.

Please check us out if you're in need of crystal caps.

Bob Thompson

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