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

1. LapDigest News for Issue No. 200 - Fri 02/05/99
2. NEW: Coloring Agates with Silver Nitrate
3. NEW: Tumble Start
4. RE: Montana Agate
5. RE: WTB: Montana Agate
6. RE: Problem With a Slabbing Saw
7. RE: Problem With a Slabbing Saw
8. RE: Problem With a Slabbing Saw
9. RE: Problem With a Slabbing Saw
10. RE: Hollowing Out Cabochons
11. RE: Hollowing Out Cabochons
12. RE: Backing of Gemstones for Setting
13. RE: Coloring Agates
14. RE: Ivory Flakes for Tumbling
15. NEW: Mineral Image Contest
16. FS: Montana Sapphires
17. SHOWS: U.K. (Scotland)


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<MSG1>

Subject: LapDigest News for Issue No. 200 - Fri 02/05/99

When you send in a response to a query, make sure you have
only one topic in that response. Don't answer two queries
with one response. That messes up the thread. That is:

ONE MESSAGE, ONE TOPIC

Anyone look at the two new pages on the website? Were there
any problems with the member's links page (did I screw up
your entry?)

Did anyone look at the equipment manufacturers address and
website page? Any comments? Any ones I have overlooked?
Lemme know!

Hey gang - have a great weekend, and remember--

Have fun!!

hale
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Subject: NEW: Coloring Agates with Silver Nitrate


Larry wrote:

<<About coloring agates and other stones "Sinkankas'"
Gemstone and Mineral data book has several very good
formulas for coloring agates and other stones. One that he
doesn't mention is silver nitrate, it can be used to create
some pretty interesting effects.>>


So I (Hale) wrote and asked him to expand his remarks on
silver nitrate. He replied:

------------------------
OK, a bit more about using "Silver Nitrate" in the gemstone
world.

First off you will need to go to your local camera store to
get silver nitrate. It is used to process film. The most
common use for it is with pearls, it used to be referred to
as "French Black" in the pearl industry. It also works
pretty well on matrix opal that just doesn’t take a good
sugar/acid treat. The idea is to soak the material in the
silver nitrate in the dark. You can use heat but as I recall
not over 200 degF. Then take the material out, pat it dry,
and then expose it to sunlight at which time it will turn an
interesting black to silver/black.

If you want to do this with agates or jaspers I would look
for material that has banding that is a little porous so
that it will accept the silver nitrate. The more porous the
material, the darker it should become.

If there are camera buffs out there they may be better able
to explain how this works.

Larry McCoy
cutter12
lm-@primenet.com
-----------------------------------------------------------
If anyone tries this or has tried it in the past, write and
let us know your experiences with it. I phoned three camera
shops (which sell supplies) and none stocked it. However I
did get a recommendation for a supplier so it might not be
too hard to get. Here we are talking about a silver nitrate
solution in water and not silver nitrate crystals, which are
quite toxic. See MSDS at
http://chem-courses.ucsd.edu/CoursePages/Uglabs/MSDS/silver
.nitrate.soln.-baker.html -- it lists the hazards as
WARNING--CAUSES IRRITATION. HARMFUL IF SWALLOWED OR INHALED.
AVOID CONTACT WITH EYES, SKIN, CLOTHING. AVOID BREATHING
VAPOR. KEEP IN TIGHTLY CLOSED CONTAINER. USE WITH ADEQUATE
VENTILATION. WASH THOROUGHLY AFTER HANDLING. hale
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Subject: NEW: Tumble Start


Hale:

For years I have been using a powder called "Tumble Start"
when tumbling stones in my vibratory tumbler. I mix 1/8 tsp.
to 1 oz water and dump it into the tumbler. It thickens and
turns the water blue (in powder form it is off-white). Its
purpose is to help the grit adhere to the rocks. What I'd
like to know is: What is the stuff? I have this feeling it
is something quite common and inexpensive. So far, I know of
only one source to buy it. Being a frugal Yankee by nature
I would like to find where I could buy it in bulk instead of
by the ounce. Anyone?

Paul H. Miller
kabal@ctaz.com
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Subject: RE Montana Agate


Hi Hale - Your last digest is very good and it is saved in
my files. I have the same question someone else had.
Where can I find Montana Agate cabs?

Ann
ZubinUbi@aol.com
-----------------------------------------------------------
It was nice hearing from Ann. She grew up 4 doors away and
went to school with my children. When she wrote it was a
very nice surprise!!! hale
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Subject: RE: WTB: Montana Agate


Cornelius Flaherty (Conb777@aol.com) asked: "Where can I
find a supplier of Montana agate?"

1 - Bill Carrothers, a member of the list, with a web page
at http://www.carrothers.com/billyboy/lapidary/index.htm
also tells me he has slabs for sale. On his website, he
shows pictures of the slabs available, and prices.

2 - Nash Perrine, also a member of this list, with a web
site at http://www.infolink.morris.mn.us/~eperr, also says
that he has some for sale. He says: "Yes I would say I
can be a source for the Montana agate. I would have to
find out via rock shop or else to price per pound. The
agates (as I wrote earlier) are somewhat hi graded already.
When I collected them I candled them as much as I could,
right out in the field, and left the so-so's right where I
found them. I'll find out a price per pound and let you
know.

3 - The Gemshop, in Cedarburg, WI (www.thegemshop.com)
advertises in the latest issue of Rock and Gem magazine
that they have some select material available for $12/lb .
I have no connection with them but know them to be honest
and reliable.

3 - Alta Vista lists 34 web pages which satisfy the search
requirements: +"Montana Agate" and +slabs. The first six
of these are

http://www.montanagemstones.com/slab.htm
http://www1.shore.net/~lanelap/amcutgal.htm (Lane is a mbr)
http://www.harmons.net/slabs.html
http://http://www.batb.com/slabs.html
http://www.jhm.com/slab.htm
http://www.batb.com/rough.html

I am not vouching for the quality of the dealers or of the
agate, but here ARE nine sources!

hale
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<MSG6>

Subject: RE: Problem With a Slabbing Saw


Hi all

When a saw gets to be 24" in diameter it begins to operate
a little different than one of a smaller size, say 8" or 10".

You said your older saw cut well until it got about halfway
through a slab but it had a wobble in it. A saw that large
has to be tensioned, i.e., it should not be perfectly flat,
even if it is brand new. Here are some of the reasons for
the wobble.

The old blade has likely heated up a number of times and
has some areas in it that are softer than others and when
it is stressed, like when it bites into a stone, the rim
wants to turn slower but is prevented by the drive shaft so
the blade buckles a bit. The more it is stressed the more
it buckles and the hotter it gets and with larger cuts it
only gets worse.

It is assumed that a suitable lubricant is being used. The
lubricant has two jobs to do. A...it has to provide
lubrication between the blade and the stone, that is while
the blade and the stone appear to be touching there has to
be a fine layer of oil between the two. And B... the excess
lubrication has to be of sufficient quantity to carry away
the heat built up in cutting and then be deposited into the
sump for cooling and reuse.

Some metal may have been deposited around and over the
diamond at the blade edge, the hottest part. You can regain
the cutting edge of your blade by cutting part way through
a common piece of brick. This will wear away the pieces of
metal embedded around the diamond but leave the diamond grit
in place.

A blade that has been tensioned means that it has been
slightly dished (saucer shaped) at the factory, either by
pounding or rolling around the center of the blade to expand
the inner section a bit. Now hen the blade begins to spin
centrifugal force (greater at the blade rim) exerts a pull
directly out from the hub and the blade tends to flatten, if
it slows down the dish shape reappears but enough tension is
generally produced to keep a wobble from starting. WARNING..
Stop the moment a wobble appears as the blade is on it's
way to self destruction. If you can't stop the blade get out
of the way. Less someone takes this too literally be assured
it will not happen with blades smaller than, say 12 inches.

Tensioning a blade isn't for everyone, I suggest you send it
back to the manufacturer or bring it to a saw filer who has
experience in lumber mills, no one else qualifies.

In this case I suspect that your feed is mechanically driven
and as the blade gets deeper into the stone it is feeding
much too fast, the rim speed of the blade is very important.
Try disconnecting the feed mechanism and feed by hand only
enough to keep the blade near it's speed when it is freely
rotating, then adjust the feed rate to suit, if you can.


Leo Doucet......Fredericton, NB......Canada......
sg2788@brunnet.net
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Subject: RE: Problem With a Slabbing Saw


Possibly the vise or rock holder track or the moving arm
they are mounted on is out of adjustment and not
perpendicular to the arbor shift. Take a stick, clamp it
in the vise so as to just touch the side of the leading
edge of the blade.( Without the saw running, of course.)
Check the travel of the vice. Assuming the blade is
straight, the stick should still just touch or almost touch
the side of the trailing edge of the blade. If there is a
gap or if the stick binds, things are out of alignment.

Regards,
Bob Boston
rvb@ihot.com
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Subject: RE: Problem With a Slabbing Saw


When you say it "Stops in the Middle" of a stone do you mean
that the saw quits running (such as if there is a motor
problem,) or are you referring to using a force feed system
of some type? If so is it belt driven? If so, it could be
that the belt is a little to large and when it gets hot it
slips. If you using a shaft driven unit, the problem may be
that you were pushing your cuts a little to fast for the saw
and the area where it stops could have damaged threads and
may need to be rethreaded)

Gil Shea
legal@mtaonline.net

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Subject: RE: Problem With a Slabbing Saw


The first thing I would do is mount a screw driver blade or
metal rod in the vise so that it just touches the side of
the blade when it is to the back. Push the vise forward and
see how the blade rests against the blade as you go forward.
If the blade stays just touching then there is no problem.
If the blade pushes into the blade or falls away from the
blade you will have to align the vise with the blade.

A very simple problem that people forget to check is the
tension of the belt. As belts break in and or wear, they
stretch and loosen. Every once in awhile they should be
checked.

I hope it's a belt and not an alignment. The alignment
takes time and effort.

Regards

Steve Ramsdell
sramsdel@prairienet.org
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Subject: RE: Hollowing Out Cabochons

Hollowed out cabs used to be referred to as "Carbuncles", it
is a very effective way to lighten up materials like garnet
and amethyst that are too dark. Almost any stone that comes
out too dark when finished can benefit from this. I use a
Foredom tool to grind out the material and then wooden dowels
to finish it. You don't always want to polish the hollow;
sometimes a matte finish looks better as it doesn't cause the
eye effect in the cab. This is a good way to keep a nice
high dome on a too dark stone. Give it a try; it doesn't
take long to do.


Larry McCoy
cutter12
lm-@primenet.com
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Subject: RE: Hollowing Out Cabochons


Very dark transparent garnets can sometimes be lightened
enough by hollowing to use them as gemstones.

Rose Alene McArthur
obmcarthur@clearwater.net
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Subject: RE: Backing of Gemstones for Setting


Another item that works well for a cushion between a cab
and mounting is foam plastic egg cartons.

Check your super market for eggs packaged in foam plastic
1 dozen cartons. The plastic has a relatively smooth, dense
surface & is about 1/16" (2 mm) thick. It can be compressed
a little also. It's a little thinner & smoother than
Styrofoam hot drink cups.

Dave
gemstonesetc@gci-net.com
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<MSG13>

Subject: RE: Coloring Agates


I have not heard of the hot oil method, but I have heard of
heating agates in sand . The way I remember it, you put
clean sand in a pan, add the agate and cover it with sand.
After putting it into the oven, the oven heat is increased
one hundred degrees at a time. I cannot remember whether
the agate is left at each increase in heat for an hour or
half an hour, then is left in the oven to cool to room
temperature.

Rose Alene McArthur
obmcarthur@clearwater.net
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Subject: RE: Ivory Flakes for Tumbling


Hi,

I agree, this recipe (1/2 cup Ivory flakes to a 3 pound
load) does a great job of burnishing stones. I use this same
combination but add a tablespoon of baking soda to help
control the gas.

Sky Paxton
paxtons@jps.net
-----------------------------------------------------------
I've also found that baking soda DOES help control gas!
(Sorry - I just couldn't restrain myself!!)
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Subject: NEW: Mineral Image Contest


NEW Mineral Image Contest

Hi Hale and others members of the Digest,

Lapidary is nice and to take look at the product of our
efforts is even more fun. So I put one and one together and
decided to make pictures of the minerals and agates I own.
I'm doing this for many years and now and then I teach
amateur photographers how to make pictures of the minerals
at our mineral club. That's why I'm always interested in
nice pictures.

By my search (surf) on the Internet for these nice pictures
I came across a Norwegian site which has a mineral image
contest. When there are any members who would like to take
look or participate, the address is:

http://home.sol.no/~eltollef/div/entries.htm

Hale, I don't know if I crossed the "borderline" of the
definition of Lapidary, but I think that you and the members
would like to know about this.

Robert M. B. de Jager
>From the northern flat part of the Netherlands.
rmbdejager@freemail.nl
-----------------------------------------------------------
Yes, Bob, this does cross the line but knowing that we have
several members who are interested in agates and photos and
such, and being in a great mood today, I decided to include
it as a little extra.(smile)
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Subject: FS: Montana Sapphires


We're having a sale on our Montana sapphires from the Rock
Creek deposit. These are blue-greens and top quality stones.
5mm are $30 per carat, 4.5mm are $25 per carat, 4mm are $24
per carat. We also have some 2.25mm fancies(blues, yellows,
pinks) for $10 per carat. You may reply any time but we
can't respond until Feb 15.
Thank you.
Deb and Dave McClain
Mac's Gems
macsgems@aol.com
http://www.freeyellow.com/members2/macsgems/"
-----------------------------------------------------------
Deb & Dave: I assume these are cabbing materials. We do not
advertise cut stones or materials for faceting. hale
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Subject: SHOWS: U.K. (Scotland)


Hello Digest Members,

As a new member to the Digest and a member of the Scottish
Mineral & Lapidary Club I regularly get sent information on
Gem, Mineral & Fossil shows which are mainly abroad.

(Shows or fairs are a rare occurrence in Scotland) I though,
for all you prospective visitors to this small island, that
I should pass on the following dates that have just arrived
from Celtic Minerals. (A one man business)

If you happen to be across here on holiday it's somewhere
else to visit along with the usual tourist sites.

I may even be demonstrating lapidary under the Club banner
at the Edinburgh show.

The dates I have are

1. Aberdeen, Amatola Hotel, Anderson Drive, Aberdeen -
10/11 April

2. Edinburgh, Capital Moat House Hotel, Clermiston Road,
Edinburgh - 29/30 May

3. Penrith, North Lakes Hotel, Ullswater Road,Penrith - 7/8
August. (Admission is £2 adult / £1 junior / £5 family with
the venues being open 1000-1700.)

Alec McCreadie
ablo@glencourse.freeserve.co.uk
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