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. 215 - Fri 6/25/99
2. NEW: Upgrading from a Cabmate
3. NEW: Tumbling Potch and Color with Matrix
4. NEW: Rotten-stone
5. NEW: Giving Agate Slabs That Wet Look
6. NEW: What is Lapis Nevada?
7. NEW: Do-It-Yourself Drip Tank
8. RE: Large Scale Rock Tumbling
9. RE: Large Scale Rock Tumbling
10. Re: Large Scale Rock Tumbling
11. RE: Sphere Making Motors?
12. RE: Sphere Making Motors?
13. RE: Sphere Making Motors?
14. RE: Sphere Making Motors?
15. RE: Sphere Making Motors?
16. RE: Sphere Making Motors?
17. RE: High Speed Engravers
18. RE: Cutting Rocks w/ A Big Saw
19. RE: Chrysoprase Table Tops
20. RE: Blue Opal & other Cutables
21. RE: Blue Opal & other Cutables
22. RE: Blue Opal & other Cutables
23. RE: Blue Opal & other Cutables
24. Re: WTB Vise Part from Frantom 20" Slab Saw
25. FS: Slabs and Opal
26. WTB: Slabbing Rough


Subject: LapDigest News for Issue No. 215 - Fri 6/25/99

This is a big issue, so let's get right to it! Here are
several items:
The Digest has received several notes on interesting topics
in which the writer completely omitted his/her name. Since
we have never had problems on this list with abuse of or
violation of privacy of our members, I'd like to ask that
you do use your name - at least your first name - when you
send in an item.
Fred Warn sent a query to the last issue (#214) about
tumbling large numbers of large stones. In this issue, Jeff
writes about the theory of large-scale mass finishing,
including notes on large equipment, and Kreigh writes
about large tumblers. Somehow all of these should be
together. So I am changing their names to Large Scale Rock
Tumbling so they will all be in one thread! (George Butts,
please take note.)
The Eastern Fed. of Min. and Lap. Societies (EFMLS) will
hold its Annual Convention on August 6-8, 1999 in Ramada
Conference Center, New Carrollton, MD, (off the Washington
beltway). Events will include delegates meeting, cracker
barrel session, auction, awards banquet and the editors'
breakfast, all open to the public (tickets required for the
banquet and breakfast). The show will feature up to 60
dealers, special exhibits and field trips to the Smithsonian
(and behind the scenes) and to the Rockville quarry.

I'll be there. If you go, please look me up! For more info,
contact Bruce Gaber at or at 301-654-7479
Vance McCallum, a longtime member of this list, is trying
to find info on Star Diamond (blade) company. Apparently
they are out of business or were taken over. Anyone know
what happened to them, and who is currently doing repairs
on their blades, please send this info to LapDigest (We also
want to know to keep Mfgrs list current.)
Hey Guys, Enjoy and have fun!


Subject: NEW: Upgrading from a Cabmate

My wife and I are considering replacing our Graves Cabmate
with something else. Trouble is, we don't know what "else"
should be.

The main reasons we're interested are the convenience of
being able to just move from wheel to wheel instead of
changing wheels/disks, and being able to use water coolant
all the way through pre-polish. We cut a fair amount of
opal, and keeping it cool this way seems like a good idea.
I've tried to cut some corundum on the Cabmate, and once
you go off the wet wheel onto the dry diamond disks, it
heats so quickly that the stone would melt the wax and go
flying every few seconds.

Our club uses Genies, made by Diamond Pacific(DP), and they
seem to have a good reputation. DP also makes a Pixie which
appears to differ from the Genie only in using smaller
wheels (4" vs. 6") - I assume the motor is smaller. The
size doesn't seem that important considering the smaller
pieces we tend to cut. (Am I missing something here?)
There are also other machines from Graves (the Cab6) and
I'm sure there are other suppliers, too.

I'd appreciate recommendations from folks with opinions on
the more complete cabbing machines. If you've been through
this upgrade, I especially want to know what you think!

Bob Lombardi W4ATM in Melbourne, FL (ex-WB4EHS) or
Bicycling, telescope making, optics, astronomy, Short-wave,
ham radio and far too many other interests to list.

Subject: NEW: Tumbling Potch and Color with Matrix

Hello all,

I have several pounds of opal rough. I think it's what is
known as potch and color. It has easily brushed away

What I am hoping to know is this: can I put it all in a
tumbler to wear away the loose matrix before I start to
hand cut it? I plan on cabbing some of it and carving the
rest with diamond burrs.

Thank you,


Subject: NEW: Rotten-stone

I've been recently reviewing the classic "Treatise on Gems"
by Lewis Feuchtwanger (1838) and especially the sections
dealing with chalcedony and chalcedony gems. One of the
polishing compounds referred to is "rotten-stone" (p. 45)
and "rotten-stone" on a tin plate (p. 102).

Does anybody out there in "LapDigest World" know where
"rotten-stone" might be available. Sinkankas (in Gemstone
and Mineral Data Book, p. 72) described it as a deeply
weathered siliceous limestone.

I would like to try some out as a recreation of historic
lapidary techniques.

Thank you.

Roger K. Pabian

Subject: NEW: Giving Agate Slabs That Wet Look

Someone wrote, sometimes ago on some unknown mail list:

<<I recently purchased some really nice thin slices of
agate. They look great when wet. What ways or types of
coatings can be used to keep a wet appearance?>>

Dan Z answered (and said I could use his answer):

Try Armorall, the stuff used on car dashboards and tires.
It brings out the color, just like water, but does not
leave a false-looking gloss. It can be removed with savasol
or, probably, alcohol. Apply a small amount with a soft
cloth, and buff until dry.

-dan- (personal) (Rock Shop)

Subject: NEW: What is Lapis Nevada?

I've stumbled across pictures on eBay of something called
"Lapis Nevada". It certainly doesn't look like the lapis I
know. It is kind of pink and green; very pretty. Can someone
tell me more about this?

k parker

Subject: NEW: Do-It-Yourself Drip Tank


You do like items about home made lapidary equipment. Here
is an unusual one.

My faceting machine came with a plastic tank with drip-rate
controlled by an anodized aluminum threaded rod. Shortly,
the rod corroded either from our local water or from the
surfactant used to prevent scratches from swarf. That was
replaced by a brass and stainless steel valve which did
control drip rate but often clogged.

My only alcoholic drink is a glass of wine each evening.
Almaden (not an endorsement) has recently introduced an all
plastic valve with a rotational handle to control flow on
its boxed wine . I have adapted one to my drip tank. It
provides almost infinite control and hasn't clogged yet.
Serendipity. If you don't drink box wine ask a friend.

Not all Almaden box wine has this type of spigot so look
for the almost square "punchout" within a printed circle.

Ivan Saddler

Subject: RE: Large Scale Rock Tumbling

I have a working knowledge of large tumblers and vibratory
finishing equipment (tubs, barrels, and bowls, some of the
larger stuff is well in excess of 100 cubic foot capacity).

I also have experience on how to line and reline almost any
type of finisher with polyurethane, and have done some work
with neoprene, which would be the lining that often defines
the final geometry and which lasts upwards of 10k to 30K
ours of operation. One of my when "I-get-to-it projects"
will be to make a mold to line the small polyethylene tubs
that hobbyist use. Or even to replace the polyethylene bowl
with an all urethane bowl.

The basics of tumbling / mass finishing are as follows:
There are several different situations.

Media-on-part: Parts are finished in a moving media, which
is often ceramic or plastic doped or impregnated with some
type of abrasive: AlO3, SiC, silica, glass fiber, feldspar,
etc. Some natural media products are also used, such as
wooden shapes, walnut, coconut shell, or corncob.

Media is available in many geometric shapes with various
grades of cutting action. Media shapes include cones, stars,
cylinders, tetrahedra, cubes, balls, trapezoidal, prismatic,
free form, triangle, etc. If you can imagine a shape, it is
probably available.

Red Rouge is often used for the red metals, but is a royal
pain because everything is sight becomes dyed red (you,
your car and house, your neighbors house, your skin, etc.)

Part-on-part: Often used for stampings or die cast parts, as
the name implies the only things in the process would be the
parts; this process uses the parts to burnish or debur each
other during the process.

Burnishing is typically done with hardened steel shot, die
castings and the like. Think of it a peening of the surface.

Different compounds can be used in the mix for cleaning,
including various mixtures of surfactants, soaps, acids,
alkalis, cleaners, and de-greasing agents. One of my first
jobs, the owner of the company was so cheap that he used
common toilet bowl cleaner for a compound. It worked, but
burned like hell if you had any open cuts on your hands.
And if you didn't have any, they soon developed. Compounds
can and are used with all of the above. Or just plain water
is often used.

I consider tumbling rock to be a mix of part-on-part and
part-on-media with abrasive added to speed up the action.
The abrasive is kind of like a micro media.

The lining materials used are typically two-part TDI
polyurethane, and some of the newer technology is gearing
to MDI polyurethane. Polyurethane and its application is
the source of my income, if you really are interested in
differences between TDI and MDI, or want to talk about an
application, or need to talk about a re-line send me an
e-mail. In rough terms the cost of a urethane reline can
be up to $100 per gallon of urethane applied subject to
mold cost if necessary. This includes sandblast and
priming. Simple flat surface tumblers don't require a mold
so figure a bit less. Some of the older stuff uses bonded
and vulcanized neoprene, but without expensive tooling it
is hard to get much more than a uniform covering for the
steel below (neoprene is not my stick). Generally though
urethane is superior to neoprene. In retrospect the abuse
that the lining can take is truly amazing. If any one is
really stuck on Neoprene I don't know of some applicators,
which can do such work. I recently paid something like
$100 ea. to do two small 1/2 cubic foot units, one of my
quotes was $200ea for the same work, go figure.

Cement mixers will work, and for the price that is not a
bad way to go: $300 for the basic up to $1000 + for
contractor series mixers. The user will probably want to
cover the opening with visqueen and duct tape.

If anyone is interested building their own large tumbler,
say 10 cubic foot plus, drop me an e-mail and I can discuss
the basic construction of such units. You will need access
to 1/4" plate steel and means to cut it (torch or plasma)
and a suitable welder (stick okay, but MIG preferred),
along with the ability to work with bearings 1-1/2" dia,
and shafts, possibly machined.

I hope that this helps, or at least in informative.

Jeff in Kalamazoo

Subject: RE: Large Scale Rock Tumbling


Buy some earplugs. I don't use my 12 inch tumbler often,
but when I do everyone in the house complains about the
noise. It has a rubber lined steel barrel, but big rocks
make big noise.

I've seen tumblers made from 55 gallon drums. Two parallel
shafts (about 4 inch pipe) on a 4x4 frame, one driven by a
motor, and the drum rides on them (just like the little
ones). Use a different barrel for each grit, and save the
cost of the rubber lining by using the newer plastic
barrels. It might be cheaper than converting a cement mixer
as you can use salvage auto parts (drive shaft assembly) to
get bearings of an appropriate size.

I'm also from Michigan, and agree that we must collect
gravel since the glaciers provided 20 feet or more of it
over everything of interest in the area. Good luck with
your project. Let us know how it came out.

Kreigh Tomaszewski
Please visit our family web pages at

Subject: Re: Large Scale Rock Tumbling

Hi Folks, Hi Fred

On my last foray to Europe I met a chap in (I believe)
Gelsenkirchen in Germany's Ruhr valley who tumbled stone in
industrial quantities, many tons a year. The rough stage
tumbler was of specially fabricated steel construction: a
flattish barrel about six feet in diametre and 18" - 20" in
width. It was not rubber lined, but rather lined with a
special blend of concrete mixed up with silicon carbide grit
in place of sand. I do not remember for certain whether he
added additional coarse grit or not but think that probably
he did.

Medium and fine stages were tumbled in stainless steel beer
barrels picked up as brewery discards and also not rubber
lined. I'm not sure whether the polishing barrel was lined;
I believe not. However I think he added crushed walnut

Hans Durstling
Moncton, Canada
Freelance writing. Feature stories, technical ad copy, clear
manuals, bid documents, simple english, videos, speeches.
Email for publication and client list.

Subject: RE: Sphere Making Motors?

Fred Gillis said:

<<The original Lap Journal plans called for "Dayton"
shielded gear-reducing fractional motors. My Internet
search revealed nothing on Dayton Motors anymore.>>

Hi Fred:

Try any Grainger industrial supply store; Dayton is one of
their names. I think they've got a web site, probably, but I'm not sure. Anyway, Grainger has
stores all over the US.

Grainger has one of the best catalogs I've seen in a long
time. Go to a store and ask for one! hale

Subject: RE: Sphere Making Motors?

The Dayton motor that Fred G is looking for is available
from WW Granger Inc. Their web address is, this is a wholesale only supplier.

Pete Poillon Jr.
They may do wholesale sales, Pete, but they have always
sold to me as an individual. hale

Subject: RE: Sphere Making Motors?

Richardson's use copier motors. Their phone number has
appeared in the LD many times.

Tim Fisher, 1995 President, Pacific Fishery Biologists
Ore-ROCK-On Rockhounding Web Site
PFB Information

Subject: RE: Sphere Making Motors?

The name DAYTON is a brand name placed on many motors and
related products, sold by the firm W.W. GRAINGER. They
have offices in most major cities and large stocking
warehouses. Check your local phone directory and they
should be there with what you need. Hope that helps.

David Beaty

Subject: RE: Sphere Making Motors?

Try and do a "find" for gearmotors. You'll
need the Acrobat Reader to view their catalog - it's in pdf
format. They have several pages of gearmotors.

Jim Schnell

Subject: RE: Sphere Making Motors?

Dear Hale,

I saw that one of your readers was looking for a source for
sphere machine motors and thought I would pass this along.

My hubby recommends a catalog called "Surplus Center." They
are at PO Box 82209, Lincoln, NE 68501-9973. Their catalog
doesn't show an email address but their FAX number is
402-474-5198. Their toll-free number is 800-488-3407.

They have all kinds of motors and other parts and equipment.
Hope this helps.

Mary Sharp

Subject: RE: High Speed Engravers

<<Has anyone used them for engraving on rock slabs or for
other lapidary purposes? I would appreciate hearing from
you about your experiences with these tools on any
lapidary media.>>


I use a Graver Max made by GRS at work. It is made for
jewelry work. It has a high speed rotary handpiece (300,000
or 400,000 rpm) and very low torque, you can easily stop the
carving point by placing your finger on it. This low torque
prevents the carver from applying to much pressure and
heating up the carving point. Also the spent air is
expelled over the tool thus keeping the tool cool also.

It works very well for carving stone using diamond tools,
of course diamond is the only carving points that would be
suitable for carving nearly all stone. The only drawback
I can see with the machine is it's cost and you do need a
compressor or some source of compressed air.

Ralph Graves

Subject: RE: Cutting Rocks w/ A Big Saw


Get out your yellow pages and look up the local concrete
cutting and breaking company. They usually have saws up to
36 inches and come to your place to work. You might have to
dig holes in your yard to bury the stones to be cut so they
look like surface concrete. I won't guarantee this service
is cheap, but neither are the size blades they use. And if
you don't have one in your yellow pages, either check a big
city nearby, or call some of the construction companies in
your area and they can refer you to a nearby contact.

My Dad expanded his house some years ago and had them out to
cut the 18 inch thick basement wall to make a doorway into
the new basement section (they left a big hole in the new
floor, pushed the cut slab over into it, and cemented it
into the floor). When they was done he had a beautiful cut
across the Michigan gravel (including jasper and one agate!)
in the cement that he finished with clear polyurethane so he
could enjoy the stones. It was just too pretty to paint over
to match the rest of the basement walls.

I've copied Hale since this is the third time I've given
this advice this year in response to questions like yours
and he may want to publish it.

Kreigh Tomaszewski
Please visit our family web pages at

Subject: RE: Chrysoprase Table Tops

Hello Hale,

I just received LAPIDARY DIGEST for issue #214. First I
want to thank you and your editors for your efforts. I am
prompted to reply to the thread concerning chrysoprase table
tops and the response from Craig White, specifically where
he says, "I am often asked if we produce back lit tables,
statues with internal lighting or 'stained glass' style
panels. We don't, but if any one does, I would love to hear
from them."

I have produced stained glass windows and Tiffany-style
lampshades for 20 years and have completed ten translucent
stone lampshades so far. I have recently completed setting
up my shop so that I can produce stone panels and lampshades
more efficiently. My dream is to retire from my job as a
computer systems control analyst and create translucent
stone panels, lampshades, and carve petroglyphs and stone

If anyone on this list has material they would like to have
made into a panel or lampshade I would love to hear from
them off list. You can see an example of one of my stone
lamps at Please note there
is an underscore between wolfrun and creations that does not
show up because of the link underline. I also have .jpg
files of my lampshades, petroglyphs, and sculptures that I
would love to share with others.

Thanks again for all your efforts,

Gary A. Betts
WolfRun Creations

Subject: RE: Blue Opal & other Cutables

Terry mentioned in his reply that he had never seen the
other minerals that Gladys was working with. We would like
to direct you to our website:
We have a lot of pictures of Gem Silica Chrysocolla from
Arizona. It is quite a nice material, and comes in many
grades and a variety of blues and greens. Right now, the
largest mine (Ray Mine) has had a cave-in so the quantities
will be scarce for a time until they decide to get around
to digging it out.

Paul & Cathy Gallagher
Gallagher Minerals

Subject: RE: Blue Opal & other Cutables

(Reprinted from Rockhounds, with Permission)

Regarding the Blue Opal; It's not fire opal, but a deep
blue material. It takes a nice polish, but it's soft like
opal. Not that great for rings.

Gem silica is Chrysocolla impregnated with silica, so it's
as hard as quartz. The best material is a deep electric blue
and comes from AZ. The Peruvian material is more of a
greenish color, but is still pretty. It’s prized because of
it's color and hardness.

It's worth buying but be careful. Anything with copper can
be toxic. Cut it with lots of water and don't breathe the

Hope this help.


Ben Hyman

Subject: RE: Blue Opal & other Cutables

[Reproduced from Rockhounds with Permission of Author]

I have done some chemical tests on the so-called "pink opal"
from Peru, and a friend of mine did XRD on it. We came to
the following conclusion: It is really SILICIFIED
PALYGORSKITE, and not opal at all! Opal exists in hundreds
of localities worldwide, but I don't know of any other
locality for silicified palygorskite, so this makes the
pink stuff more interesting, I think, from the point of view
of both mineralogy and gemology. Also, since it isn't really
opal, the lapidarists among us don't have to worry about it
slowly dehydrating and cracking like many opals do, and it
probably wouldn't be as heat-sensitive as opal during

Alfredo Petrov
Cochabamba, Bolivia

Subject: RE: Blue Opal & other Cutables

In case you want to see pictures of the BLUE OPAL and PINK
OPAL (PALYGORSKITE?) please go to:


Subject: Re: WTB Vise Part from Frantom 20" Slab Saw

Wanted to Buy: Front part of the vise for a 20 inch Frantom
slab saw. This is the vise that looks like a car jack, i.e.
serrated edges that you move the front part of the vise in
and lock it down.

tim vogle>
Tim Vogle Enterprises
404-738-3548 beeper

Subject: FS: Slabs and Opal


For sale: slabs by the pound, a real nice assortment of
various slabs (agates, jaspers, petrified wood, obsidian,
etc.) $10 a pound plus shipping.

Also lots of real nice Australian opal Lightning Ridge,
Coober Pedy, boulder, Airport, 8 mile, Mintabi, & Lambina
fields from $5 an ounce and up (some larger pieces available
that will cut nice cabs also. I also have some nice Oregon
opal and some Spencer Idaho opal.

tim vogle>
Tim Vogle Enterprises
404-738-3548 beeper

Subject: WTB: Slabbing Rough


I am looking to buy slabbing material, If you have items
you want to sell or need slabbed, please contact me.

tim vogle>
Tim Vogle Enterprises
404-738-3548 beeper

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