LAPIDARY DIGEST
Administered by Hale Sweeny (hale2@mindspring.com)
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This list digest contains the following message subjects:

1. LapDigest News for Issue No. 55 - Tues. 9/2/97
2. NEW: Trim Saw Lubricant
3. NEW: Peruvian opal info?
4. NEW: Opal vs Super-glue
5. RE: Fire Agate
6. RE: Fire Agate
7. Re: My Slab Saw Binds
8. Re: My Slab Saw Binds.
9. Re: My Slab Saw Binds.
10. RE: My Slab Saw Binds
11. Re: My Slab Saw Binds
12. RE: My Slab Saw Binds
13. RE: Fixing Nevada Opal
14. RE: Vibratory Lapping


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<MSG1>
Subject: LapDigest News for Issue No. 55 - Tues. 9/2/97

I have changed the name of a file in the Archives from
lustrous.txt (or something like that) to LUSTER.TXT. If
you haven't been able to get 'lustrous', try 'luster.txt'.

We welcome Lance Kanaby as a member. Lance helped me start
this list, and gave me lots of good advice; I hope we can
return the favor. Lance runs GemData, Mine Design & The
Spectrum Network at http://www.gemdata.com. At that site,
you will find his interactive "Gem, Mineral & Jewelry
Show Calendar", a list of gem shows, and other things.
Welcome, Lance.

And thanks to Carol Bova and to Karl Case for very complete
descriptions of how to cut fire agates. These will be pulled
out and placed in the Archives as separate items.

Hope you all had a fun but safe Labor Day!

hale
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<MSG2>
Subject: NEW: Trim Saw Lubricant


My husband & I are new to lapidary but we bought an old but
serviceable Lortone 8" trim saw. I am a jeweler so I want a
wide range of rocks cut to design with. Right now we are
cutting with oil and it is Soooo messy and stinky plus you
can't see what you are doing because it coats the plastic
shield so much. At shows and in Lapidary Journal I've seen
things like "Lube Cool." I like the benefits they list, but
what's the down side?

We will cut things from boulder opal to jasper to granite
and basalt. Then we'll cut nothing for a few weeks. What are
all your thoughts on using water + additives in your saw?

Thanks!

Carla
foxon@europa.com
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<MSG3>
Subject: NEW: Peruvian opal info?


I just purchased a small piece of rough of Peruvian opal--a
wonderful sea foam green/blue. Other than it from Peru and
is called opal, can anyone else tell me more about it. My
piece has black speckles in it.

How easy is it to cut and polish? Anything special I should
know about cutting and polishing it? You know - all the info
that is fun and interesting.

Thanks!

Carla
foxon@europa.com
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<MSG4>
Subject: NEW: Opal vs Super-glue

Does anyone know a safe way to remove an opal from an setting
which was reinforced with super glue? Would nail polish
remover work or would it damage the opal?

Cathy Gaber
bg@his.com
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<MSG5>
Subject: RE: Fire Agate

<<I have always had a fascination with FIRE AGATE. My
questions are --
What is a good procedure/process to use in cutting it?>>

Most fire agate cutters that I know use diamond cutting
tools, after removing the white or brown unwanted matrix
with conventional saws. Since the dust is toxic, use
breathing protection, and it is safer to cut under water
with a Foredom tool, carefully and slowly removing small
amounts to bring deep seated fire closer to the top.

<<How do you know whether a piece of fire agate has fire
in it?>>

Usually you cannot tell from a piece of rough unless a
window has been cut and polished to show the deeper fire
colors. This is the reason most sellers of rough will
offer you material with windows. Otherwise it is a case
of learning to spot small seams of fire. A good point
source light, such as a small tensor lamp or a pen
flashlight helps to spot the fire, while slowly turning
the piece to examine it carefully.

<<How do you avoid cutting thru the fire?>>

Fire Agate is really carved rather than cut in the
conventional sense. This is the tricky part. Hoping to find
deeper fire, it is very easy to cut too much, and suddenly
all the fire is gone. Mostly it takes a lot of practice and
patience, and careful examining as you go. I cant tell you
how exactly, it is a skill learned by doing.

<<Where is a good source for it at reasonable cost?>>

Fire Agate is never cheap. And apparently getting more and
more rare. The ads in rockhounding journals are few and far
between in recent years. Most domestic material comes from
Arizona or California, and there is some good material from
Mexico. Quartzsite has been a good source in recent years.
I prefer to see what I am purchasing, that is a matter of
personal choice, of course.

<<Are there any fee digging areas where you can dig your
own?>>

I have not kept up with the fee digging sites recently, but
I can point you to a former good source, write them and see
if they are still offering this service.

Send a SASE to Cuesta Mines, 4582 N Sierra Rd., Kingman, AZ
86401. They are near Kingman, AZ north on I-40 South to
Oatman, AZ where wild/tame desert burros roam the streets
begging for a handout.

Hope this helps a little.

Karl
karlc@sedona.net

-----------------------------------------------------------
Ed. note: Karl is an old friend who has retired and who
has given up lapidary. He tells me that he has some fire
agate left which are for sale: a couple of hundred fire
agate cabs, free form, mostly ring size, some larger
pendant size, cut and polished. Also fire agate rough,
with windows cut and polished. They average about the
size of an English walnut in the shell. Anyone interested
may contact him at the address shown. I bought some of the
rough and a couple of cabs and am pleased with what I got.
hale.)
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<MSG6>
Subject: RE: Fire Agate

bill collins wrote:
<<I have always had a fascination with FIRE AGATE. My
questions are -- What is a good procedure/process to use
in cutting it? -- How do you know whether a piece of fire
agate has fire in it? -- How do you avoid cutting thru the
fire?>>

Because there are many, many layers in the best pieces, you
almost have to cut through them to get the really intense
effects. You could by lots of luck and careful work with a
Dremel or Foredom hand tool, "peel" away one layer to get
just one color. Or cut a piece that has only one layer of
color. But the joy of fire agate is to bring out as many of
the rainbow colors as possible, and this involves removing
parts of some layers and leaving others. The botryoidal
(bubbly) form makes this very easy to do. Just follow the
general shapes, abandon the concept of calibrated shapes or
sizes, and let the stone's natural flow and colors guide you.

>From the side, if it isn't already broken off at some point,
grind a little on the edge to see how the color layers are
running. You should actually see layers with brown in
between. You can't tell what colors they are until you
expose them, and you need to guess where to stop before
grinding through the last one! There are many articles in
old Rock & Gems and LJ's. I'd volunteer to look one up,
but we're in the middle of packing for a move and all my
mags are packed already.

As far as what to use, you are dealing with a VERY hard
stone. It's chalcedony with layers of limonite and/or
goethite believed formed from a gel situation, because it
forms in bubbles with layers. You will swear sometimes that
it is harder than anything you have ever cut before...and
it can eat diamond tips like you wouldn't believe. Last time
I worked fire agate, I used phenolic tips with diamond
compound of various grits and a little extender. Too much
only flies off, so use it sparingly!

Another way is to grind down wood dowels to the size you
want to use, and again, use diamond compound with extender.
Keep each point (whether wood or phenolic) in a separate
plastic bag, and wash your hands and the stone thoroughly
between changes of grit. You can roughly shape on a diamond
wheel or trim off excessive amounts of colorless chalcedony
first, but when you're getting anywhere near color, take it
slow and easy! I spent 45 hours once over a couple of weeks
working on an intricate piece that had red, yellow, green
and violet, and just when I thought I was ready to take it
to polish, tried to even up a color area and went through a
last layer and created a colorless hole right in the center.

Fire agate got me into lapidary, but I now work with opal.:>

<<Are there any fee digging areas where you can dig your
own?>>

My personal favorite is Opal Hill Fire Agate Mine with Nancy
Hill and Howard Fisher in Palo Verde CA, just southwest of
the Blythe and the AZ border. From Palm Springs it would be
east on Route 10 to Highway 78, follow the 78 signs and
zig-zag around the fields, to Palo Verde. It is a tiny town.
At 4th St., turn right and follow the signs. You will be
crossing a farm yard, carefully please!, and will be going
9 miles across the desert to the mine. Signage and ruts
are pretty clear. A regular vehicle can do it if it has
good clearance and you take it easy, but I feel much more
comfortable in my pickup. Do not try it in wet weather!
That sand is slippery and you have to cross a couple of
washes and lots of potholes.

The mine is open Nov. 1 to May 1. There is no phone
connection up on the hill, but you can write to Nancy c/o
Opal Hill Mine, P.O. Box 497, Palo Verde, CA 92266 for full
details on fees and directions. There are group, weekly
and senior citizen rates. Last time I was out, I think the
daily rate was something like $15 or $20/day. You keep what
you dig or find weathered out or inadvertently thrown away
by novices who don't know what to look for! (Nancy and
husband Howard will make sure to show you where to look, how
to dig, and what to look for if you're willing to listen.)

What you didn't ask was about the digging itself: this is
hard rock mining! Come prepared with rock hammer, sledges,
chisels, etc., a brush or whisk broom to clear away the dust
and sand to see what you're working toward. A bucket or
heavy sack, thick gloves! and shoes (boots). Knee pads are
nice. Watch for the occasional scorpion..another use for the
whisk broom...Bring your own food and water, hat, sun screen,
etc. There is no water on the hill. And if you're staying
over, bring a chair to lean back and look up at the stars in
the desert night. If you've got a portable UV lamp, bring
that for night looking too. Fire agate doesn't fluoresce,
but the calcite around it sometimes does, as well as some
other goodies. Look before you pick up anything lime green
..scorpions fluoresce intensely!

I've heard that Nancy is using portable oxygen now because
of silicosis acquired from dry cutting with no respirator.
So please, even with diamond compound, use a good mask that
filters fine particles. If you get there, tell Nancy I was
asking for her!
Carol
.------------------------------------.
| Carol J. Bova bova@bovagems.com |
| The Eclectic Lapidary e-zine |
| http://www.bovagems.com/eclectic/ |
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<MSG7>
Subject: Re: My Slab Saw Binds


bill collins wrote:

<<I have a large (20in) home built slab saw. There is a
problem with it. It binds up about 1.5 to 2 inches into the
rock. As you are looking at the blade, the right edge of the
diamond appears to be wearing. It appears to run true; I
purchased a larger washer to brace the blade but nothing
worked. IDEAS???>>

Check the alignment and travel of the vise. It may be
traveling at an angle to the blade. May have to use a dial
indicator to get an accurate reading.

Earl English
ewenglish@blueridge.net
-non-commercial republish permission granted-
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<MSG8>
Subject: Re: My Slab Saw Binds.

What I suspect is happening is your saw vise is not in
line with your blade. It does not take very much to cause
that.

I use a dial gauge but you can use a pencil also to check
the measurement. Put the pencil in the vise and run the vice
up to the blade. Move the pencil out until it just touches
the blade, and clamp the pencil. . Now move the vice down
the blade and watch the pencil. Does it continue to just
barely touch the blade ? If it presses harder or moves
away from the blade you will need to align your vice with
the blade. Since I do not know what you have I can't offer
a suggestion on that other than usually you move the vice
tracks to align the setup.

Ken Wetz
kwetz@acun.com
http://www.acun.com/~kwetz
- non-commercial republish permission granted --
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<MSG9>
Subject: Re: My Slab Saw Binds.


Bill -

I have had 3 causes for such as this.

The first was that the saw blade was worn out enough that
it would not cut material as hard as I was trying to cut.
The only solution was a new blade (ouch!)

The second was that one of the pulleys on the belt dry had
become partially loose and started spinning on the drive
shaft as the saw resistance built up in a deeper cut.
Solution - redress shaft, new pulley, new belt.

The third was that the blade had been entered into a rock
and did not start a straight cut. As the cut went deeper,
the blade tried to cup and the resistance stopped the blade.
(Once the blade actually became cupped and would ALWAYS try
to cut a curve) Solution - start cutting somewhere else
being very careful to get a straight start and/or out the
blade on a flat surface and check for cupping. Sometimes it
can be pounded flat again, sometimes a new blade is required.

Good luck!

Mel
mela@galstar.com
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<MSG10>
Subject: RE: My Slab Saw Binds


it sounds to me that it's possible that the saw blade and
the vise don't travel in parallel planes. if the vise is
moving toward the blade a little with each turn of the screw,
it'll bind up even if the blade is true. try attaching a
marker of some sort at the leading edge and trailing edge of
the vise, and running the machine as though cutting some
material. after the full pass, both markers should be the
same length. if the trailing marker is cut shorter (or
longer) unparallel planes is probably your problem.

al macneil
youtookmyname@hotmail.com
non-commercial republish permission granted
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<MSG11>
Subject: Re: My Slab Saw Binds


A dial indicator is the most precise tool for measuring blade
run-out. Once you have reduced the wobble to a minimum it is
necessary to check that the rails the vice rides on are
parallel to the blade. Next to check is feed rate. Too high a
feed rate can cause the blade to drift and bind. I was taught
to always stop the feed and allow the blade to "set" as soon
as it was a short distance into the material. Be sure the
blade is picking up the coolant, and that you are using the
right coolant for that blade.

Gary Ogg
Columbia, SC
gary.ogg@worldnet.att.net

Non-commercial republish permission granted
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<MSG12>
Subject: RE: My Slab Saw Binds


I had the same problem when I got mine. My problem turned
out to be the alignment between the blade and the vise. As
the vise moved on the rails it pulled the material away from
the blade. Suggest you fill a 1/2 gallon cardboard milk
carton with plaster of Paris (wait for it to set) then run
it through. When it almost is completely cut through, turn
off the saw. You should be able to see then if the blade and
vise are parallel. The plaster of Paris is so soft it
shouldn't bind.

You may have to adjust the alignment of the rails or the saw
blade arbor. Which ever seems easiest, I'd try that first.
Recut a milk carton. It worked for me.

david tuttle
dtt@net-magic.net

non-commercial republish permission granted.
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<MSG13>
Subject: RE: Fixing Nevada Opal


Peter asked: << Anyone know anything about fixing cracky
Nevada opal?>> Ken Wetz answered in part: << I do remember
years back a way to stabilize the stuff was to wrap it in
wet paper and put it in a tightly closed plastic bag and
let it dry out slowly...<snip>..>>

It's going to be as dry and stable as it's going to get
after about a year. If it's going to go all cracky, there's
really nothing to do except Opticon it if you really want to.
If it's only partly crazed, after a decent drying out time,
you can try carefully trimming away the crazed part, or
grinding it down to solid material.

David Burton, former pres. of the American Opal Society,
had a huge contra luz opal from Virgin Valley that he sent
out to a cutter in the desert for faceting. It had to be
cut several times before it stabilized. Started out as 88
carats, ended up as 43.43 carats. There's an article about
it in Vol. I, Issue 3, "The Colors of Heaven" with a photo.

I've seen the stone in person, and it is incredible! The
picture is not retouched at all!
Carol (aka VP, AOS)

.------------------------------------.
| Carol J. Bova bova@bovagems.com |
| The Eclectic Lapidary e-zine |
| http://www.bovagems.com/eclectic/ |
'------------------------------------'
-- non-commercial republish permission granted --
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<MSG14>
Subject: RE: Vibratory Lapping


Ray Killian's message (Message 7 in Issue 52) about
vibra-lapping had an oversight. If you plan on heating
lead on a stove, either use a camp stove outside or open
all windows and have an exhaust fan operating. The lead
when heated will give off fumes which could, when inhaled,
lead to breathing problems or lead poisoning.

Precautions should always be taken. Using a simple paper
mask, like those found at garden supply stores, would help.
A mask should be used when doing heavy rough grinding on
wheels, even if you use a lot of water.

David & Barbara Tuttle
dtt@net-magic.net

non-commercial republish permission granted.
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