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

This list digest contains the following message subjects:

1. LapDigest News for Issue No 271 - Sat 4/8/2000
2. NEW: Comments on Probert's Rock Encyclopedia
3. RE: Protecting Druzy Quartz from Grit and Polish
4. RE: Cutting Something Concave
5. RE: Cutting Something Concave
6. RE: Cutting Something Concave
7. RE: Cutting Something Concave
8. RE: Difference - Dendritic and Moss Agates
9. RE: Difference - Dendritic and Moss Agates
10. RE: Adhesive for Doublets and Triplets
11. RE: Colors on Raytech Diamond Disks
12. RE: Colors on Raytech Diamond Disks
13. RE: Araldite
14. RE: Inexpensive Cabbing Machine
15. RE: Mineral Oil as a Cutting Lubricant
16. WTB: Pietersite Cabs
17. FS: Ruby in Zoisite


Subject: LapDigest News for Issue No 271 - Sat 4/8/2000

James Hutcherson (see below) said, about the contest for
the best write-up on how to build an inexpensive cabbing
machine: "If this is a real contest, I would offer up a
parcel of rough to beef up the prize pile. I would also
build one of the above units myself to prove its concept,
and submit it in an attempt to win back my parcel of
rough :) YES, James (and everyone), it is a real contest
and I do have a parcel of rough set aside with very nice
and special cutting rough for the winner. Contest details
and requirements will be in next issue.

We will start the Mentor program slowly with only one or
two appointed Mentors, and monitor usage. If they get
pushed, we will appoint more, and if they are completely
idle, we will reduce their number. If you pose a query
which would be interesting to the wider group, the
Mentors will give you an answer, and we will post it in
the Digest for wider answers.

>From time to time, I give the URLs of Websites which
should interest you as lapidarys. If you have any you
think the whole list will enjoy, send them to me, please!

An Internet friend, Mel Albright, uses the following as a
signature line, and it says exactly what I want to say to
all of you:

Hug or call someone you love today!


Subject: NEW: Comments on Probert's Rock Encyclopedia

A quick look at the Probert's Encyclopedia of Rocks and
Minerals mentioned in Digest #270 indicates that members
should be cautioned concerning the spelling of a number of
minerals and rocks. This encyclopedia appears to be based
on English usage and rock and mineral names are often
spelled differently from common American usage.

Some of the information is also suspect. i.e. "Amethyst
is quartz colored with manganese." I believe that later
research indicates that amethyst is colored by an ion of

Ed Elam

Subject: RE: Protecting Druzy Quartz from Grit and Polish

Hi all,

I need a little help this time. I was lucky enough to score
a good sized chunk of azurite-malachite. After trimming a
couple nice specimens for my cabinet I decided to slice the
rest for cabs. In addition to the massive majority there
were a few patches of very nice drusy azurite. I want to
shape and polish the edges with out damaging the fragile
druse. Any suggestions?

I thought of coating the druse with paraffin to protect
things while I worked on the edges. Then using acetone or
another solvent to remove the paraffin when I was done. I
don't have enough of the drusy azurite to feel comfortable
experimenting though. So I was hoping a wise and experienced
lapidary digest member would know what to do. I looked in
the archives but found no joy this time. Any suggestions
would be appreciated.

Thank you,

Paul Boni
Boulder, CO
Paul: We discussed this back in Issue 259 (1/13/00) and an
answer was given in Issue 261 (2/23/00) involving the use
of lacquer to protect the druzy; the letter was written by
Ted Robles who I know to be an expert and careful lapidary,
and whose opinion I value and trust. Someone else might
have another method (and if so, I hope they will write)
but this is one method which has been used and tested. If
you don't have that issue, you can get it from the Web
Archives. hale

Subject: RE: Cutting Something Concave

I cut optical dishes in gems, but nothing in the diameter
that you are asking or, however you can purchase wooden
handles from Menards (or any other supply store ) that
have a single screw on the back side. Most have a rounded
surface, of different radiuses. Pick one that is close to
what you need. You will need at least 4 as you will be
using different grits.

I use diamond 325, 600, 3000, and then polish with cerium
oxide for my final polish. Also I would suggest starting
with a diamond tool sold by Dremel. It has a radius on the
end. (Wal-mart & K-mart stores sell them) Place in a drill
(preferably a drill press), put your glass lenses, centered
under the diamond tool, and use water as coolant on this
step. After you get a good start and a locating hole you can
then start with a hand drill with the wooden handle with the
screw in place on the back. Put diamond paste (325) with oil
(baby oil, etc.) and work the hole out to the size that you
need with the hand drill (move the drill from side to side)
the radius of the wooden handle needs to be the radius the
you need on the back of the crystal. Work all grits or
diamond from coarse to fine in the same way. Polish with
cerium oxide, and water.

Hope this helps.

Just something to look for, all crystals that I have seen
do NOT have a smooth radius as the hands would rub the edges
of the crystal. Check this before you start. If more info.
is needed e-mail me.

This works for me on the optical dishes that I use on my

Howard Broderson

Subject: RE: Cutting Something Concave

How do you cut and polish a concave 'hollow' in a piece of
lapidary rough?

First find a 'grit holder' that has a convex end that
matches what the concave depression your going for. The
grit holder should be true to round and have a shaft you can
chuck into a drill.

IMHO, the easiest way to get this is to start with a dapping
block, or some other positive mold that shows concave
depressions. A dapping block is rather common for most any
silversmith or jeweler. First spray your block with a oil,
say, a squirt of pam.

Now fetch some two part putty type epoxy. I find the
ceramic or metalized epoxies work best here, they seem to
setup harder than liquids and work up rather easy. Use 1
part hardner, 1 part resin, and 1 part grit. Mix it all up
together and knead well. Push into your dapping block and
add a mandrel to the exact center of the mix. The mandrel
should be meaty enough to get a good grip with a drill. I
normally use a 1/4" mandrel with a washer and nut on the
end to give good purchase in the epoxy. Most putty type
epoxies have a short working time, so you have to work fast.
Visually inspect and give a test spin on your drill to make
sure its true and doesn't vibrate.

Now chuck your new tool into a drill, have a drip tank of
water ready, and start grinding. If you happen to have a
drill press laying around, its a bit easier. You should
make tools in various grits, I usually use at least 2 or 3
grits, starting with an agressive 100 grit, going to around
350/400, then finally 600 or 700. If you use graded grits,
things work better. But you can also use tumbler charges.
To make a polish head, don't add any grit at all to the
epoxy, add the polish compound to the head as your working
instead. This doesn't work well with grits btw as the grit
will have a habit of removing the epoxy instead of the rock
if its not embedded in the epoxy.

I use this method to make various shapes of polish and
griding points for carving.

James Hutcherson

Subject: RE: Cutting Something Concave

Hello Tom,

I think Hale had the answer if the inside curve is deep
enough to clear the hands. The other suggestion of cutting
down a larger watch crystal would also be expedient. I was
unfortunately unable to use either of these short cuts when
asked by a customer to make a new crystal for a fairly
valuable antique ladies Piaget. The problem being the
crystal was approximately 13 mm cushion square and required
a fairly deep recess to clear the hands but needed a flat
bottom to fit the case correctly.

I had to cut a perfectly round dish in the middle of a
square. I ended up mounting a flat slab of quartz on the nut
of my faceting machine and strapping my Foredom to the quill
and I was able to produce the required depression exactly.
I used a small diamond carving wheel in the Foredom at about
1/2 speed and with the faceting machine turning at about 60
rpm. I polished the recess with homemade diamond paste
liberally applied to wooden golf tees also held in the

I realise that this process is neither simple nor does it
use common lapidary equipment but it did produce a perfect
result.....i.e. I got well paid.


Subject: RE: Cutting Something Concave

I use a foot-pedal variable speed dermal tool with a variety
of diamond bits to cut concave surfaces in minerals. In
bright light, I further grind the surfaces with automobile
carbide paper or cloth, using a hand-cut 1" or 1-1/2"
diameter round plastic disc as a backing. I use automobile
antifreeze container plastic because, after some
experimentation with other plastics, this is the flexibility
I want; not too stiff and not too soft. I like the yellow
plastic, it's easy to see when you are working with it or
drop it on the floor.

Most of the work is free-form cabbing done on opals dopped
on a stick. I put the opal on an upside down tomato can
with a 75 watt light bulb inside to do doping with jewelry's
wax. This decreases the fire hazard of an open flame. I
have never lost opal fire with this method, but to be sure
of not overheating on a convoluted surface, I glue the opal
to the stick with a child's blue liquid glue, which is
slightly soluble when left in water to loosen the bond.

I do this work dry, at slow to medium dermal bit speed, and
clean/wash the opal after each grit (200, 400, 600, 1000,
1500) to avoid contamination. Wash with water only, never
use soap, detergents, solvents, etc.

When I do a standard opal cab, I use a lapidary wheel wet,
always use the jewelry's wax and pop it off after leaving
it in the refrigerator (I don't sit with it in the
refrigerator any more, I'm getting to old to stay in the
cold overnight.) <grin>

Bruce Murray
Robert Bruce Lapidary
Schenectady, New York

Subject: RE: Difference - Dendritic and Moss Agates

Without observing the agate, these appear to be moss agates.
Dendritic agates usually have black or dark brown tree-like
structures that are often confined to a more-or-less single

Moss agates generally have irregularly distributed,
filamentous, root-like or membrane like or pond moss-like

The terms moss agate and dendritic agate have often been
used interchangeably in the past. This is probably not a
correct practice. The mineralogy of moss (chlorite,
celadonite, etc.) is different than that of dendrites
(Manganese oxides and iron oxides). There are some examples
of dendritic agates from Montana and Kazahkstan and moss
agate from India on the agate page at:

Hope that helps.


Subject: RE: Difference - Dendritic and Moss Agates

I'll quote from "Webster, 'Gems, Their Sources, Descriptions
and Identification', fourth ed. pp. 222-223":

<start quote>
Agate often contains inclusions of other minerals which
assume tree-like (dendritic) forms. Such stones are known
as moss agates, and the included 'vegetation' may be black
(probably manganese dioxide), green (possibly chlorite) and
red (an iron mineral). Sometimes two or even three coloured
'trees' are in the same stone. In England and America the
term mocha stone is used synonymously with moss agate, but
in European countries the green moss agate alone is known as
moss agate while the black and red coloured dendrtic agate
is termed mocha stone. Some dendritic agates show the
dendrites so arranged as to resemble landscapes, and such
agates are termed landscape or scenic agate.
<end quote>


Jaap Bos

Subject: RE: Adhesive for Doublets and Triplets

When using epoxy 330, if you heat the stone and then apply
the epoxy this will thin it down and make the bubbles come
out easier. Be sure not to get the stone too hot, just good
and warm. You could also mix the epoxy on a piece of foil
and warm it on the dop pot before applying. Doesn't take
much heat, just enough to warm the epoxy . This seems to
work for me.

Don Brenholtz


Subject: RE: Colors on Raytech Diamond Disks

<<The boxes say that I have a 280, 600, 1200 and a diamond
polish disc. The colors are: dark brown, blue, red and gray.
Can anyone positively match the colors with the grits?>>

The 280 is brown, the 600 is red, the 1200 is blue, and
the polishing, gray.

Dick Friesen

Subject:  RE: Colors on Raytech Diamond Disks


Their e-mail address is "". Checked in
their catalog and couldn't find any reference to color on
any of the cutting disks. Only on their Ultralaps! lol
Please sign your name next time!! Thanks - and thanks for
the email address for RayTech. hale

Subject: RE: Araldite

Hi Hans,

Good memory -- that was more than six months ago! Yes, I'd
recommended Araldite, not so much because it's runnier
(though it is), but because it cures to about the
consistency of Plexiglas, if not harder. (As opposed to most
commercially available epoxies, which tend to retain some
degree of elasticity, and therefore, can do some pretty
interesting things to your laps, when trimming doublets and

The easiest way to find Araldite seems to be by contacting
either W. Grainger's (the contractor's supply house), or by
asking your neighborhood pharmacy for the name of their
Ciba-Geigy/Novartis rep, and contacting him or her, since
it's distributed by them. The one other shot you might have
is to contact Super Glue Corp, in Hollis, NY, whose
Brazilian factories manufacture it. (Well... you did ask.)

When you mix the stuff (2-part), if you'll use a toothpick,
and *gently* fold the two parts into one another, you can
eliminate the "permanent bubble" problems that'll plague
you, otherwise. Good Luck!

Glad to help out!

Best Regards,
Doug Turet

Subject: RE: Inexpensive Cabbing Machine

First, you should always make a visit to all the
rockhounding stores in your area. Get out the phone book,
drive around, check them all. Normally your gonna find
someone who wants to help you out. Asking them about used
equipment is a sure way to go for starters. Ask them if
there is a local club/group and where they meet. Then,
ask the club if they have used gear laying about.

Second, check your local community colleges to see if they
offer lapidary classes. Lots of them do, and lots of them
have wonderful labs full of gear. I learned to cut rock at
Spokane Falls Community College, and they had every tool I
could imagine, lots of help and tons of rough to start with.
Cost was tuition for a semester.

To build your own cabbing machine, the hardest piece to find
is the mandrel. This is the shaft you mount wheels to. It
will have a pully on it for drive, and a couple bearings to
support it. The bearings should be sealed, and capable of
holding up some load.

You can buy prebuilt mandrels in various shapes and sizes.
If you spend sometime with your phone book, and calling
around to tool makers and metal workers in your area, you
should be able to scare up a mandrel rather cheap.
I recommend getting something at least 5/8", threaded at
least 3" deep, and the threads should be right and left
handed on each end.

Ive seen these prebuilts in various woodworking catalogs for
~$25.00, the Kingsley North catalog lists one for $36.15.

Taking the time to call around a local metal shop will save
you more though. You might just find the perfect mandrel
cobbled together from parts on thier scrap/junk heap. Or,
you might be able to chat up one of the folks to threading
a chunk of shaft stock to your specs.

Should all else fail, you can buy a piece of shaft stock,
and add slip on arbors. These are made to fit on the end
of a motor directly, but, in the case of a lapidary unit,
you dont want your drive motor that close to water :) This
will run around 5 to 10 bucks a side, and you have to make
sure you get the proper threading for the proper side (left
and right handed threads)

You can also buy premade lapidary mandrels, aka, arbor
shafts. Some of these will be ready to rock, just add
wheels, drums, etc, and go. Others are just the arbor and
require drip pans and the like. They all seem to average
from 100 to 200 bucks.

So, now you got a your mandrel. This needs to be mounted
with room for the drive belt, and the wheels on either end.
You can screw it down to a block of wood say, or make a
custom stand with drip pans from aluminum or

Mount up a motor with a belt, far enough away to be
protected from water spills. You can get a motor used from
most any applicance repair shop, junk yard, etc.

Add a couple drip pans, and perhaps a top cover. Make sure
you make a visit to your local petstore and get some
aquarium tubing and a plastic gang valve, and rig up a drip
water system with an old bucket, 2 liter bottle, etc. Just
make sure you have something to hold the water tank above
your work and gravity will do the rest.

Get yourself a wheel and some belts. Again, check with your
local rockshop and see what he has used for wheels. Figure
a 6x1" 100 grit wheel will cost you 25 bucks or so. A
6x2-1/2" drum will cost you another 20 bucks, or 40 bucks
for the expandodrum. Belts run 2 bucks a piece or so. I
find that I can get a good polish up using just 1 roughout
wheel at 100 or 220 grit, and then 1 400 grit belt, and a
600 grit belt. Finishing off on leather with raybrite A,
or some other nice polish.

If you got the money to splurge, get a diamond saw blade as
well, this adds another 40ish bucks, but its well worth it.

You can build a tray that fits snugly into your drip pan,
that acts as a table saw top. Just make a piece shaped
like a [, the legs long enough to cover the arbor and the
nuts, washers, and fittings used to hold a blade on. The
top should have a slot in it big enough for the blade to
fit through. Then all you need do is put the blade on one
end of your machine, fit your saw tray on top of it, and
have a trim saw ready to go.

If this is a real contest, I would offer up a parcel of
rough to beef up the prize pile. I would also build one of
the above units myself to prove its concept, and submit it
in an attempt to win back my parcel of rough :)

James Hutchinson


Subject: RE: Mineral Oil as a Cutting Lubricant

I have just bought and cleaned a 12in. "ROCK" slab saw in
which I intend on trying the oil. I have done a little
slabbing on another 12" portable saw but no cabbing or
polishing at this time. I would like to convert the
portable saw to a water cool solution such as LUBE COOL
for a traveling unit.

Now to the business of mineral oil. The following is the
information off the 5 gal. can which is sold as tractor
transmission fluid.


Defined by IARC as class 1 mineral oil.
Described as Rust and Oxidation inhibited Hydralic Oil
with "anti-foam"
Chemical listed as Carcinogen or potential Carcinogen
National Toxicology program "NO"
IARC Monographs "YES"

Sold at Diamond Shamrock Stations for $14.99/five gallons.

I agree, Adam, this is a good price (~$3/gal). I still
prefer FOR MY USE a lighter food grade mineral oil. Mineral
Oil is NOT carcinogenistic, so if the MSDS for this product
says it is, it must be due to the additives. (I really
think you may have misread the label - which isn't hard to
do with some of the health warnings!! I think the statement
that the Nat. Tox. Program says: 'NO' means that it is not
carcinogenic) hale

Subject: WTB: Pietersite Cabs


Would you or any of the many knowledgeable lapidarys out
there know where I can find nice pietersite cabs. I have
seen lots of beads or carvings, but not nicely polished
cabs. Different shapes if possible, not just the typical

Thanks again, hale.

Ali :=)
Ali Casado

Subject: FS: Ruby in Zoisite

Hi Hale:
We have 10 tons of Ruby and Zoisite and would like members
to have a shot at some of this material. We have put up a
preliminary Picture Gallery and contact information. It is:
( It's selling for $6.00/Kg
for regular rough, and $50.00/pound for the high quality
(at least75% Ruby)


Dave Salyer

To unsubscribe from the Lapidary Digest, send a message to, with the word UNSUBSCRIBE DIGEST as
the subject of the message. Other commands you may use are:
SUBSCRIBE DIGEST to join, HELP to receive a page of help
instructions on the use of the list, and DIR to receive a
list of names of all files in the Archives.

The command <GET filename> may be used on the subject line
(without brackets, of course) to obtain a copy of the file
named "filename". Type filename exactly as it appears in the
directory, including the extension txt. Do not cut-and-paste
filenames into the subject line.