Edited and Published by Hale Sweeny
Web Site: http://www.lapidarydigest.com
Associate Editors: Geo. Butts, JR Shroeder, Steve Henegar,
Margaret Malm, Sam Todaro, and Ed Elam
This list digest contains the following message subjects:
1. LapDigest News for Issue No. 283 - Sat 2/10/2001
2. NEW: Quartzsite and Tucson 2001
3. NEW: Heat Treating Agate to Improve Appearance
4. NEW: How to Enhance/Stabilize Turquoise Color
5. RE: How to Identify and Cut Iris Agate
6. RE: How to Identify and Cut Iris Agate
7. RE: Drilling Holes in Stones
8. RE: Making Triplets from Meteorite Slices
9. RE: Bead Mill and Bead Making
10. RE: How to Calculate Pulley Sizes on a Saw?
11. RE: How to Work Amber
12. CLASSES: Lapidary Classes in Minneapolis
Subject: LapDigest News for Issue No. 283 - Sat 2/10/2001
In the last issue, in an item about Ed Elam's channel work
classes this summer, I forget to add Ed's e-mail address
under his name. That address is email@example.com.
The Digest received five messages about calculating pulley
sizes to get a desired blade speed. When we get multiple
answers to the same query, and when they are essentially
the same solution, our policy is that we will select the
simplest and most straight-forward answer, and go with that,
adding any pertinent info from the other letters to the
published response. All persons who submit responses will be
acknowledged, of course, as done below.
Also received is the following endorsement for Joe Adam's
sphere machines from Bob Morgan <firstname.lastname@example.org>:
<<Joe Adams <email@example.com> most certainly does
produce very reliable Sphere Machines. I purchased one just
over a year ago, and can attest that it is a very workable
machine. It has turned out many spheres for me and will
continue to do so for quite some time I am sure. Again,
thanks Joe! I am one happy "sphererer"!>>
That is it for now.... Will send the next issue out on or
about Sunday Feb 18. I hope all you guys will note that
Valentines Day comes in flor days -- it's a perfect time
to tell those you love that you DO love 'em. (Tho ANY time
is perfect for that!!) Have a good and safe week.
SUBJECT: NEW: Quartzsite and Tucson 2001
Quartzsite was cold this year, highs in the low 60s lows in
the low 30s with a couple of days of rain. Clouds was still
open, we were told last year that the Highway Department was
going to build a new Off-Ramp there but they haven't yet so
the show was still on. Unfortunately over half of the
dealers made arrangements to move to the new "Desert Gardens
Gem Show" before Clouds found out they could have the show.
Dick Cloud told some of the dealers that there would be room
for them next year no mater what the Highway Department did
so there will be at least a small show there next year.
It seems to me that there are more people showing up every
year, the traffic seems to be much worse with reports that a
hour or more to get from Tyson wells to the Main Event was
common, less than a mile. Still plenty of free BLM camping
area at least.
Maybe I'm just getting harder to please but it seems to me
that high quality lapidary material is getting harder to
find at Quartzsite. It is still lapidary heaven but bargains
seem to require more effort to dig out. I did find some very
good Siberian Jade and some small carvable sized pieces of
Malawi Blue Chalcedony.
Tucson is another story, it seems to me that much of the
better lapidary material has moved there (at much higher
prices). Tucson can be very intimidating for newcomers.
There are about 25 shows scattered through town, many of
which are not open to the public. The emphasis is on up-
scale finished jewelry and faceted stones but with this many
shows there is some of everything. Miners are starting to
bring their best material directly from the mine to the
shows and the works of some of the worlds best carvers and
lapidaries are available.
I saw some old Australian Chrysoprase that I haven't seen on
the US market for over 20 years, the high quality material
seem to be going to Japan now days.
The bottom line is; Southwest Arizona is the place to be in
late January and early February if you are interested in any
form of lapidary.
Subject: NEW: Heat Treating Agate to Improve Appearance
I have seen agate that was heat treated which considerably
enhanced its original appearance.
Does anyone have any information on the process of heat
treating agate? Is all plain agate likely to respond to
Norm, I have never seen agate which has been heat-treated
to improve its appearance, but I do know that flint knappers
heat treat agate to improve the flaking action, and this is
frequently done in their kitchen ovens. Any good book on
flint knapping will give time-temperature data for doing
I discussed this a year or so ago with a well-known
mineralogist on the list and he proposed several mechanisms
by which heating could improve flakability, but we did not
discuss heating to improve the material's appearance. If
anyone has anything to add to this, on the effects on either
appearance or flakability, please write it up and send it
in. Any references will be appreciated. hale
Subject: NEW: How to Enhance/Stabilize Turquoise Color
I have rough turquoise very light or white. I do not know
how to enhance and stabilize the color of turquoise rough.
How can I enhance the color and stabilize the colour of
rough turquoise. It is being done in Arizona, USA or some
where else so that it does not fade or loose the color.
I shall be thankful in this regards for assistance.
Subject: RE: How to Identify and Cut Iris Agate
<<I have a question about Iris Agate. We collected..(snip)..
iris agate there and other interesting things. Well, now, I
know there wouldn't be an interesting pattern in the iris
agate. So the next time we visited the site, I picked up a
lot of plain chalcedony. And, you know, I still don't know
how to identify the most likely candidates for cutting.
I know that I have to cut it at a right angle to the base
of the formation. Can anyone give me any more clues as to
what to look for? I am wondering if the tracing of little
fine lines radiating upwards on the broken surface is what I
should look for, or is it something else? >>
I know you have to cut it *very* thinly, 1/16th inch or
less, for a good chance to see the effect. The cut should
be perpendicular to the layers, you will know you have it
right as the material will go from pretty clear to frosted
by just turning it off-axis. It should look as clear as
possible looking in perpendicular to the slab face.
Hope that helps. It is a pretty effect, and you need strong
light from behind the slab to see the colors, which are
Subject: RE: How to Identify and Cut Iris Agate
It's really nice to see lapidary digest going again. I'll
try to add some input where ever I can. Thanks for your good
Regarding Rose Alene McArthur's query about iris agate, I
can maybe offer some insights but no certain solutions. I've
cut over 30 thousand agate nodules and have not found any
way to predict whether or not an agate will show the iris
phenomenon. The phenomenon is far more widespread than one
might imagine. Many agates may have a very narrow zone
(1/100 of an inch or so) that show a few bands that produce
iris. I like to think of iris in terms of a zone that is
sufficiently wide that one need not strain to see it (one
tenth of an inch or so). Some of the literature sources
report that about only about 1 of 20 thousand agates shows
iris. This is a gross exaggeration of its rarity. Brad Cross
recorded that up to 70 percent of the Sueco agates from
Mexico showed iris. I cut several hundred of these nodules
and found Cross' estimate was conservative---I scored about
85 percent. These were nice bands of iris 1/8 of an inch or
Brightly colored, translucent agates also show strong iris
effects. The iris is masked, however, and if the agate is
red, only the yellow and blue spectra can be seen. If the
agate is yellow, only the red and blue spectra are observed.
Nonetheless, they are very beautiful agates. Most cutters
miss this because they equate iris only with the colorless
Extremely fine banding does not seem to be a prerequisite
for iris. Some of the finest iris agates I have observed
only have 60 or 70 bands to the inch whereas others have
many thousands. The iris seems to be more pastel in the
former case and more brilliant in the latter.
My solution has been to take a thin slice (1/16" - 3/32")
off of any banded agate that may be improved by cutting for
iris. I don't always cut for iris---there can be many more
features in agates that are equally interesting and
beautiful phenomena such as stalk aggregates, sagenitic
inclusions, etc. that may be missed by going for iris.
Iris appears to be more common in amygdaloidal agates than
in thunder egg agates. I have not observed the phenomenon in
agates of marine sedimentary origin, but I have not made a
hard search for it here. I have observed it in some agates
of continental sedimentary origin.
I hope these comments are of some use. Good luck on your
Roger K. Pabian
Subject: RE: Drilling Holes in Stones
I've never seen a "good" book on drilling polished stone.
There's some tricks to it which need explaining. Broadly,
the stone is held rigidly under water and drilled with a
diamond drill in a drill press... simple? Not very! I
will explain how I do it.
THE DRILL BIT:
The drill is fine wire (3/4 mm - 2 mm diam.), diamond
coated for about a quarter of an inch. Bob Aurelius
mentioned (in LD-282/msg10) that the "Ripple" bit, sold by
Rio Grande is superior. I don't have the new Rio tools
catalog but this sounds like the Crystalite "Triple Ripple"
drill, my excellent standard for several years. It has
three flutes to aid water circulation and grit removal,
THE DRILL TOOL:
A variable speed Dremel in their drill press, outfitted with
a micro drill chuck to hold the fine drills. Adjust the
press sleeves so there is no play and the head moves up/down
easily with just a bit of a drag to neither drop nor flip up
if you let go of the handle. The drill works well at about
1/3 speed, about 10,000 rpm. Both hands are needed for the
operation so a foot switch is almost mandatory. The bit
must be chucked true without any wobble when running.
The stone has to be "clamped". It mustn't give in ANY
direction under the pressure and vibration of being drilled.
This was the worst problem to solve until I came across
"Jett Sett Plastic" from Rio Grande. Jett Sett is an
astounding material. It is a tough, hard plastic that
softens in hot water to resemble modeling clay (or window
putty), will stick to itself wet and can be formed into any
shape. It gets softer with increasing temperature to a max
of 175 F. Our Microwave has a "cooking probe", making exact
heating a snap. I just put some JSett in a cup of water with
the probe set for 175. I let it hold for a few minutes and
when I take the plastic out it is easily kneaded and molded.
BTW, 175 is "quite hot" but the low heat transfer of JSett
allows it to be handled with small discomfort.
I quickly put the soft plastic into a low form cup, press it
down to fill the bottom, push the stone into the center and
pull the plastic up snugly around the stone. The drill site
must be at exactly dead top center. When cool, the stone is
tightly locked, ready to drill.
Add water to just cover the stone by about 1/8 inch or so.
Drilling is done by a pounce - release action... bite until
you see wisps of stone dust at the drill contact point.
release, re-bite. Just pulse the bit up and down in fairly
rapid easy strokes. Hold the rock assembly steady with the
other hand. Have patience. Use a fine pin to test depth
Drill a pilot hole with smallest available bit (3/4mm) to
make a guide track to depth. Enlarge the hole to final
diameter with a larger bit. Enlargement is quick and smooth
with the pilot hole pre-drilled. Hole diameter is always
greater than the drill bit!
If you are going to epoxy in an up-eye or the like, 3/16
inch is plenty deep. Clip the up-eye stem to snug length.
Dremel folk worry about water splashing or "climbing" up
into the motor. I have never seen a problem BUT if you use
a Ground Fault Interrupter (GFI), available from any
hardware store, electrical shock can't be a problem.
You MUST have something between your eyes and the work in
progress! You will need to see the drill action up close
so a magnifying head piece is a good idea (Optivisor #3
When finished with drilling, put the Jett Sett and stone
into hot water and let soften until the stone can EASILY
While still hot, flatten the plastic to a thin strip so it
will re-heat fast next time.
Drilled holes dry out slowly (capillary). Squirt in a bit
of acetone or isopropyl alcohol with a hypodermic needle
followed by a "squirt" of air.
Much of our work involves electroplating gold "bezel" frames
on freeform cabs which need a drilled/glued up-eye for a
hanger. I worked on the drilling problems for a long time
and, essentially, the above is the result. Others may do it
easier and better but this works for me. Good Luck!
Subject: RE: Making Triplets from Meteorite Slices
Dan <firstname.lastname@example.org> wrote:
<<I want to make triplets from thin slices of Mars and Lunar
meteorites, but have not been able to find slices of quartz
or backing material. Can anyone point me to a supplier and
perhaps describe the process.>>
Having ruined a coupla' keyboards from drooling over the
items at your website in the past (grin), I'm happy to offer
Instead of quartz, investigate using synthetic spinel or
corundum. Inexpensive, and much more durable than quartz.
It's available in 'boules' (cylinders-the corundums are
split lengthwise, the spinels could be sawn) and would
already be well shaped for many of your applications.
Somewhat trickier to polish but that reflects the additional
hardness/durability. Much more fitting for your fine work!
Don't know about durability of the adhesive for actual daily
'pocket' conditions though perhaps adhesive AND rivets would
work. That would require the additional step of diamond
drilling the spinel 'blanks' before polishing I guess.
Try http://creativegems.com for synthetic and
natural facet grade material.
1 Lucky Texan
Based on Carl's comments, some of you may wish to take a
look at Dan's website: http://hiwaay.net/~dfronfld hale
Subject: RE: Bead Mill and Bead Making
I received a letter today from Dan Drouault, President of
Covington Engineering Corp., who informed me that they make
two models of 5" Bead Mills. These mills will make beads
from 5/16 to 3/4 inches in diameter. The one-speed mill
turns at 380 RPM; the two-speed mill at 380 and 250 RPM.
The fast speed is best suited for producing beads from hard
materials such as agate, jasper and jade. The slower speed
reduces the abrasive action and should be used when working
softer materials such a malachite, rhodochrosite and
turquoise. Their Model 1039 has 1 speed and retails for
$535. The other is Model 1040, which has 2 speeds and
retails for $616.
These mills make several beads at a time, and the preforms
are ground into spheres as they are rolled around between
two grooved heads, one of which is rotating.
Mr. Drouault also sent the operating instructions for their
5" powered bead mills, and these instructions will appear in
the next issue. He also volunteered to answer questions
about making beads in bead mills, saying: "I will do
anything I can to help you not only with the bead mill but
any other machine questions you may have. ...(snip)... I can
give you a more practical answer to specific questions as I
have many many hours of experience with it as well as all my
If any of you want more descriptive material on these mills,
send a request to email@example.com, and say
you saw it in the Digest!
Is anyone on the list currently making beads, either by hand
or by machine? If so, please write and tell me what you are
doing. Does anyone want to see instructions in the Digest
on simple ways to make beads by hand? What is the interest
among List members in making beads from lapidary materials?
Subject: RE: How to Calculate Pulley Sizes on a Saw?
Rita Wright <firstname.lastname@example.org> wrote:
<<My saw has a 1750 rpm motor, a 14" saw blade, and a 7"
pulley on the saw blade shaft. What size pulley do I need
on the motor shaft for optimum cutting speed? Is there a
formula for calculating this should I decide to use larger
blades on the saw?>>
Thanks Rita, for asking a question I can answer.
In John Sinkankas' Gem Cutting (my bible) he states that saw
rim speeds should vary from 2,500 surface feet per minute
(sfpm) to 8,000 sfpm with the slower speeds for harder
stones such as agate, and since most of us don't want to
change speeds we tend to run saws at the lower end of that
range, say 3,000 sfpm. He provides tables to calculate
pulley sizes but the maths isn't too hard:
A 14 inch blade has a circumference of 14 * 3.142 inches, or
44 inches or 3.67 feet. So to get 3000 sfpm, the blade needs
to turn at 3000/3.67 =817 revs per minute.
The ratio of the pulley diameters is the easiest way to
calculate the size needed so since 817 revs at the blade
is roughly half that of the motor you need a motor pulley
roughly half the diameter of the existing 7 inch blade
shaft pulley. A 3 inch motor pulley will give you a blade
speed of 750 rpm (3/7 * 1750) and therefore a blade speed of
2750 sfpm (750 * 3.67).
That will be perfectly safe for the blade on all normal
materials at the expense of taking slightly longer to cut
the softer materials. Of course if the saw has a single
speed power feed then the time taken is the same whatever
the blade speed.
I seem to have made that sound more complicated than it
really is, just remember this doesn't need to be exact -
it's supposed to be fun!
Andy Parker, Agate House Lapidary
Ulverston, Cumbria, England
Tel: 01229 584023
Editor's Note: The Digest also received answers to this
Roger Varvel <email@example.com>
Stefan Carlgren <firstname.lastname@example.org>
Tim Fisher <tim@OreRockOn.com>
Thurmond Moore III <email@example.com>
Our appreciation is given to these other responders.
Subject: RE: How to Work Amber
In issue #281, Tony Cambell asked how to work amber.
Tony, directions are given on my website as:
How to Polish Amber
Use fine sandpaper to remove crust. Follow that with medium
steel wool. Then use extra fine steel wool as a prepolish.
Polish the piece with toothpaste, car polish, or Armorall
on a denim cloth.
Let me know how it comes out.. I plan to try it myself this
And if you need amber to work on, I have amber and other
minerals for sale on my website:
Come take a look.
Subject: CLASSES: Lapidary Classes in Minneapolis
For those of you who live up here in the frozen north... My
partner, Mary O'Rourke and I are starting up lapidary and
jewelry making classes. We've been reorganizing the studio
to make more space, rounding up equipment and we are now
ready to offer classes. I'll be teaching a four week
Beginning Lapidary class on Tuesday nights and four weeks
of Scrimshaw on Wed nights. Mary will be teaching a
Beginning Jewelry class on Tuesday nights. Future classes
will include Intermediate and Advanced Jewelry, Intermediate
Lapidary, Casting, Wirewrapping, Enameling & Cloisonné,
Beadwork and Open Lapidary Workshops.
While the Twin Cities can boast of having four or more rock
clubs, not one of them has space for a clubhouse or lapidary
workshop. We figured this would be an opportunity for folks
in the various clubs interested in lapidary work to get
together, or for those folks who would like to try it out
before they invest in a lot of equipment. We already have
an informal wire wrapping group that gets together on
Sundays (This is almost like a Ladies Auxiliary of the
Minnesota Mineral Club, but the guys are welcome too!).
Anyone in the area (or just passing through) is welcome to
contact me via e-mail or at the studio phone number
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