Web Site: http://www.lapidarydigest.com
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This list digest contains the following message subjects:

1. LapDigest News for Issue No. 183 - Sun 12/6/98
2. NEW: Polishing Spheres
3. NEW: Any Comments on "All-You-Need" Flat Lap?
4. NEW: Polishing Petoskey Stones in a Tumbler
5. Re: Polishing Pads
6. RE: Mexican Jelly Opals
7. RE: How Do I Cab Jade?
8. Re: Polishing Jade
9. WTB: Twin Arbor Wet Grinder
10. BIO: Sky Paxton
11. AD: Gemking Public Room Announcement


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<MSG1>

Subject: LapDigest News for Issue No. 183 - Sun 12/6/98


Two messages to LapDigest were inadvertently lost this week
by failure of the software to save them (or maybe by a
boo-boo of mine!!!). One was a message from Giovanna about
Ivory flakes and the other was a message about upgrading
their CabMate. Would you please resend them?

So many people expressed interest in the Scythian background
of Roger Pabian's eagles that he put together a small
bibliography on the subject; it has been added to the Gallery
Show page at www.lapidarydigest by link.

I am still looking for more lapidary work to exhibit in the
web page Show Gallery. If you have done some which you want
to exhibit, I will need photos of several pieces to make a
show (preferable 5 or 6, but can be fewer) and a Bio. Send
files in .gif or .jpg formats.

Be safe. Hug someone you love - hugs are really important!
And have fun!

hale
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<MSG2>

Subject: NEW: Polishing Spheres


In polishing spheres I have used the imitation chamois you
buy for polishing your auto and they hold up well and hold
the polishing agent well and are relatively inexpensive
especially if you find them at a flea market.

Another good inexpensive item used to polish spheres is old
felt hat pieces which you can find at thrift stores or
garage sales for relatively nothing. You can cut them to
any size or shape or glue them to a firm backing if needed.

I recently saw some plastic like stars in the hardware
store, in 3 different sizes shaped like crosses and thought
they would make great buffers to put in with stones while
tumbling to prevent chipping. The smallest was about 1/2 in
and the largest an inch.


Lila Trudel
bookslt@aol.com
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<MSG3>

Subject: NEW: Any Comments on "All-You-Need" Flat Lap?


I have just subscribed to the list and have already learned
from it. I was wondering if any of you are familiar with a
unit know as : All You Need" or something like that. I
understand it is great for cabbing. Would appreciate any
info on this subject.

I am an amateur cabber. Would like to do a lot more, but
time does not allow most of the time. We have to rely on
purchasing most of our stones. Have never tried to facet.
We do unusual wire craft and silversmithing.

--
J. Byers
http://www.csranet.com/~phoenixe
phoenixe@csranet.com
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<MSG4>

Subject: NEW: Polishing Petoskey Stones in a Tumbler

Hale, a rock shop in Michigan was using finely ground corn
cobs, about the size of ivory soap flakes to polish Petoskey
Stone, dry and with cerium oxide and the finished polish
was excellent. It is a soft stone but would probably work
on other stones.

Lila Trudel
bookslt@aol.com
-----------------------------------------------------------
(I wrote the following to Lila)

Lila, I presume you are talking about tumble polishing the
stones, right?

(and she answered)

Yes the Petoskey stones were in an upright tumbler with an
open top and the finish on the stones was great. I had never
heard or seen this medium for polishing and was quite
impressed so thought someone else might be able to use it on
these and other stones. Lila
(Now if only I knew whether it was a rotary or vibratory
tumbler!
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<MSG5>

Subject: Re: Polishing Pads


One thing I have wondered ( and worried) about is the speed
at which the pads should turn.

I learned on a polishing machine where the 8" leather pads
turned at about 200-300 rpm. On my Pixie, and on Genies,
the pads are much smaller but turn considerably faster, and
apparently there is no way to slow them down (according to
Diamond Pacific).

I would appreciate it if someone would talk about good
speeds for polishing, or maybe good surface speeds for
polishing.

hale
hale2@mindspring.com
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<MSG6>

Subject: RE: Mexican Jelly Opals

[[I recently acquired several Mexican jelly opal cabs; one
was 5.6 carats and the other 3.5 carats. They are very
beautiful. I looked up what we had in the Archives about
cutting and polishing these opals, and saw that we had a
file (Cutting Jelly Opals.txt), but the information in that
file was not anywhere near complete enough. So I will ask
again: Can anyone on the list give advice on orienting,
cutting, polishing Mexican jelly opals? Know anything
about where in Mexico they come from and how they are mined?

Would you please write up what you know and send it in?]]


Hale:
For information on locations & mining techniques for
Mexican opal check out the October 1998 issue of Rock &
Gem. There is an excellent article by Bob Jones on
Queretaro opal, which is the main region for Mexican opal.

The opal locals were known by the Aztecs who called it
"quetza-litzle-pyolliti". According to Frank Leechman in
"The Opal Book", it first came to Europe in the first
quarter of the sixteenth century. The opal mines at
Queretaro were discovered by a peon working on the
plantations of Hacienda Esperanza in 1855 but mining did
not begin in earnest until Don Jose Maria Siurob opened
the "Iris" mine in 1870.

Queretaro is located about 160 miles by road northwest of
Mexico City. The mines are open quarries. The opal occurs
in rhyolitic rock, filling cavities in the rock, usually
completely filled cavities although occasionally opal will
be found floating loose in some cavities. It is mined by
being blasted from the hillside with explosives. The
resulting boulders are then broken up by hand to free the
opal. Other lesser localities mentioned in the references
I have are at San Juan Del Rio & Tequesquipan both of which
are approximately sixty miles east of Queretaro, Zimapan
and Vila Seca, northeast of Mexico City in the state of
Hildalgo.

As far as polishing Mexican Jelly opal goes, I am not a
professional cutter, but I have been cutting opals for about
30 years & have found a method that works well for me. If
you are going to be successful with cutting Mexican Opal you
need to be aware of a couple of characteristics common with
the material. Mexican opal is very heat sensitive, it often
has a higher water content than its Australian cousin, it
can be somewhat brittle. Before cutting a Mexican jelly I
usually leave it out of water for a couple of weeks to make
sure it is stable enough to cut. Once I am convinced a piece
is cuttable, I try to do as much of the preforming as I can
without doping the stone

When I’m ready to dop, I paint the side to be dopped with
clear nail polish & allow that to dry. Than slowly warm the
stone in the oven to about 100 degrees F. (no more than
that). When the stone is warm take a dop with hot wax and
press it to the stone. The nail polish will provide a strong
bond with the dop wax, I have yet to lose a stone off of the
dop using this method. For shaping the stone I work with
silicon carbide belts on an expandable drum. I don’t like
grinding wheels because of the shock to the stone and I do
not use diamond belts because they cut to fast. I do any
preforming on a broken-in 100 grit belt, shaping on a 220,
400, 600 then on to a well worn resin belt with 50,000k
diamond spray for final polish. Everything is worked very
wet until the final polish. Use light pressure through all
stages.

For polishing I use a medium pressure and keep the stone
moving to avoid getting it hot. If the resin belt starts to
grab too much, add a drop or two of baby oil or other light
mineral oil. If you see any kind of scratches under 10x
magnification, the belt is either contaminated or not broken
in well enough. Before polishing soft opal with a resin belt
I usually polish a couple of agate cabs to break it in.

Heat is probably your biggest enemy when working with
Mexican Jelly opal. KEEP IT COOL! One other item to note,
occasionally you’ll run across a piece of jelly which seems
to have kind of a diffuse play of colors. Hold it up to the
light, so the opal is between your eye & the light. You may
have a piece of "Contra Luz" opal. It will come alive with
color when viewed through transmitted light, similar to
"Iris" agate only much more intense. Contra Luz should be
faceted rather than cabbed. It makes a truly amazing gem.
Every cutter has his or her own methods, but the above
methods have worked well for me.

Hope this helps,
Noel
<noel@iolusa.com>
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<MSG7>

Subject: RE: How Do I Cab Jade?


<<Our assignment for stone of the month in my Houston Lap
club is (gulp)Jade (looks like spinach colored nephrite)
Anyone got advice? I heard it undercuts, so what do I do
about that?>>

Without knowing what equipment you have available it is
hard to know what the best advise is. You will have the best
results if you can dry sand on 600 grit or finer silicon
carbide and follow with "Rapid Polish" for a final polish.
Tin oxide will work if you don't have the "Rapid Polish".
Try to do the final polish quickly. Dry sanding leaves the
surface free of "orange peel" but if you spend too much
time on the final polish you can bring it back.

If you are using your own equipment, I would recommend
getting a 600 grit SC belt or disk if you don't have one.
If you are using club equipment and 600 grit SC is not
available maybe you can buy your own and bring it in.

There are several suggestions in the archives you should
look at also. I don't recommend diamond for a final sanding
or polish. It can be done with diamond but if you are only
doing one stone I think it is more work than it is worth to
learn how.

Dick Friesen
friesenr@ix.netcom.com
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Subject: Re: Polishing Jade

Hello Hale:

I have been reading the articles on jade polishing with
interest. My two cents is added here. You can republish
for non-profit.

I have polished jade in a lot of ways. Most of these
articles seem to be right on the money. The use of silicon
carbide belts does a great job all the way through
pre-polish. I also liked the worn 600 belt for this.

After the pre-polish I used one of 3 methods depending on
the type and quality of the material.

Most of the Wyoming Jade needed no more than 8,000 diamond
on a hard leather wheel. I used an old 10 in. by 2 in.
leather wheel made from combining sole leather (I have no
idea where you would get this now). The trick is to get
the stone hot.

Another trick is not to have the stone come undoped and
fly across the room or to burn.

Some people go as far as 50,000 diamond. This makes black
jade look like obsidian! Another polish is chrome oxide.
This is worked wet on leather. This is slower, but works
on a great variety of material. There was warnings on this
material for awhile. I don't know of any safety rules that
should be used.

Last is a product called Linde A. This is a commercial
product that will do a great job if worked on leather.

Some things that do not work. In other words...been there,
tried that. Felt doesn't work, it adds to orange peel.
Cerium and tin-oxide seem to be too soft of an abrasive to
get past the orange peel. In other words they remove the
softer material and leave the harder stuff. Most people were
just afraid to put the needed pressure on when polishing.
The heat is a part of the process. Just don't get too heavy
handed. I like to work more than one stone at a time. If I
feel one is getting too hot, I just switch to another.

Steve Ramsdell
sramsdel@prairienet.org
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<MSG9>

Subject: WTB: Twin Arbor Wet Grinder

Hi,

I'm looking for a Twin Arbor Wet Grinder for lapidary work.
Preferably used. If your selling one I'm interested.
Email to address below.

Thanks,

Richard Sanchez
Petraman@klty.com
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Subject: BIO: Sky Paxton


My name is Sky and my lapidary interests are in cabs and
spheres mainly but anything interesting. My favorite stones
are the agates and opals. I have a sphere machine, saws and
a cab machine.

I've been collecting since I was five but only became serious
about 5 years ago with a class taught at the local college in
cab cutting. I plan to retire in 10 years and go full time in
lapidary.

Sky Paxton
paxtons@jps.net
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<MSG11>

Subject: AD: Gemking Public Room Announcement


Hello List Members,

Hope you all had a safe and happy Thanksgiving. Just wanted
to remind you that the new "Gemking Public Room" is
available for discussing faceting, lapidary, gems and
jewelry around the clock. We staff it each week night with
volunteer hosts to talk to our visitors. Each Friday night,
we have a Feature Presentation, which currently is a
multi-week series on Beginning Faceting presented by myself.
This program will begin at 6:00pm PST.

All weekday hosted events in the Public Room begin at 6:00pm
PST each week night, and the weekly schedule is posted on
the Gemking Public Room Login Page. To access the Public
Room, use the link at the bottom of our main page at:
http://www.gemking.com

I hope all of you will take advantage of this unique
resource with which you can share and learn more about our
wonderful hobby's. To enter the Public Room, your browser
must be Java enabled. For those of you without Java
capability, we have archived all past transcripts at the
site. Hope to see you all there!

Paul Ahlstedt / Owner
P. T. Ahlstedt Mining and Mineral Exploration
1997 AGTA "Cutting Edge" Award Winners
gemking@inland.net http://www.gemking.com
Office: (909)943-4078| Fax: (909)943-4425|
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