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. 165 - Friday 9/11/98
2. NEW: How To Polish Nephrite
3. NEW: Polishing or Tumbling Chlorastrolite
4. NEW: Experiences in Cutting Opals
5. NEW: How Do I Get Started?
6. NEW: Fossicking Gemstones in Southern India
7. NEW: Cutting Cat's Eye Opal
8. NEW: Padparadscha
9. NEW: Want Advice of Cabbing Set-up
10. NEW: Field Trip
11. NEW: Cleaning NC Corundum Question
12. RE: Want Experience Info on 'Ugly Duckling' Blade
13. RE: Which Tumbler is Best?
14. RE: Turquoise Rough Prices
15. BIO: Duane Bolanowski
16. BIO: Kreigh Tomaszewski


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<MSG1>

Subject: LapDigest News for Issue No. 165 - Friday 9/11/98

Well, just when you think the rain has stopped, lightening
strikes! After putting out the last Digest, I got several
new letters and that evening, I closed the software. Next
morning, nothing was there! No address list!! None of the
replies! So if you sent in a reply, and I know five or six
of you did, please resend them!

About the question of change of policy - I want to restate
it to give everyone a chance to submit opinions. It is this:
In the future, if you subnit a query or response or anything,
the copyright is transferred to Lapidary Digest. Then every
club can use what we say in their bulletins. If you don't want
your submission reproduced, then just add the words: 'Not for
reprint', or similar words to your submission. Please let me
know how you feel about this.

As most of you know, I lost all recent files in a disk crash
several weeks ago, and they are urecoverable. So if you
had sent something recently (before the shut down), such as
polishing or Honduras opals, please resend!!!

Well, I am off to a football game weekend. Be back Sunday.
Meantime, be careful, back up your hard drive, and above all,
have fun!!

hale
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<MSG2>

Subject: NEW: How To Polish Nephrite


I am working with nephrite. My question is what are the best
polishing techniques?


Goldenctry@aol.com
-------------------------------------------------------------
(Hale's Note: Suggest you look up an article in Rock and Gem
June 1998 by Dick Friesen entitled 'Polishing Nephrite Jade'.
Dick is a member of this list and has submitted a paper on
polishing jade, but it was lost in the recent crash (or, the
recent unpleasantness), and that will be published sometimes
in the near future. Meantime, go to the library, if you don't
have that copy, and get and read it. Hopefully other members
will answer your query also. hale)
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<MSG3>

Subject: NEW: Polishing or Tumbling Chlorastrolite


I have a piece of chlorastrolite (greenstone) that I would
like to polish. My dad has a tumbler and we have had great
success with Lake Superior Agate and other beach stones.
However, we are not sure how to proceed with the greenstone.
I understand that the hardness is 5 or 6, but I have not
been able to find any info at the library regarding
polishing. What other stone would be appropriate to turn
with it and what grit should we start with?

Amy Follebout
agate@klondyke.net
-------------------------------------------------------------
(Hale's note: I had not heard of greenstone, so I looked it
up in my mineral database, and found that the real mineral
name was pumpellyite (Mg). Knowing nothing about this mineral,
I posted a query in Rockhounds and Rocks-and-Fossils maillists
asking for information on it. Here are a few of the answers:

Terry Adams wrote: "According to The Mineralogical Record -
Michigan Copper country chlorastrolite is pumpellyite (Mg)
[see page 68 Vol. 23 (2), March-April 1992. In the Keweenaw
area, it occurs in amygdules in basalt. This variety is hard
enough to cut and polish. Pumpellyite (Mg) also occurs as
tufts of radiating green crystals and is associated with
copper and calcite.

Terry Adams
<tsadamsfargo@worldnet.att.net>"

Ben Hyman, a list member, wrote:

"Chlorastrolite is a zeolite mineral, similar to Thompsonite.
It is also called "Turtleback" because many of the specimens
exhibit a checkered green pattern similar to a turtle.

It is found as small amygdaloid fillings in basalt cavities.
It is ONLY found in the U.P. of Michigan, and on Isle Royal
in Lake Superior. The chlorastrloites are quite small, often
no larger than your finger tip. Larger specimens (3" or more)
with good pattern are extremely rare, and quite valuable. It
is quite scarce, and is sold by the gram. It is only found
in the areas described.

It is about a 5-6 on the Mohs scale, and takes a nice polish.
It needs to be treated carefully, as the pattern is often skin
deep. You really need a flex shaft tool to follow the curves
of the specimen in order to polish it.

The Seaman Mineral Museum at Michigan Tech University has a
beautiful display of these stones, and there is some available
for sale at Houghton Gem and Mineral in Houghton, MI. There
is a guide up there by the name of John Perona. He resides
in Silver Dollar Bay, and he will lead you on field trips to
find chlorastrolite, datolite, and copper. He also has some
for sale. He was written up in a recent Lapidary Journal as
one of the guides for Red Metal days in Houghton.

There is also a well respected lapidary artist by the name of
Stephen Hoglund in Grand Marais, MN that makes spectacular
jewelry out of chlorastrolite, Thompsonite, agate, and other
local stones. He uses gold and is nationally renowned for his
skills. He too was written up in Lapidary Journal several
years ago.

That's all I know. Hope this helps.

Regards,

Ben Hyman
Gemlight Lapidary Studios
bhyman3431@aol.com"

Finally, Bill Cordua, another list member and a very
knowledgeable geology professor at Univ. of Wisc, River Falls,
wrote:

"Hi Hale and everyone,
Chlorastrolite is a variety name of Mg - Pumpellyite. It
occurs generally as bluish-green stiff acicular or needle-like
crystals. It forms during low grade metamorphis along with
other green minerals such as prehnite, chlorite and epidote.
It is rather common in the metamorphosed basalts of the
Keweenaw Peninsula of Michigan. Here it occurs filling cavities,
in veins and replacing the original igneous minerals in the
basalt. When it occurs as pure masses of intergrown crystals
filling old air holes (or as amygdules, to use the technical
word) in the lavas, it can take on a fine polish. The texture
and variation in green color in the stones gives them a
pleasing appearance. It can be mistaken for chlorite, with
which it is found. A hardness test will separate the two, as
pumpellyite has a hardness of 5.5 to 6 which chlorites are
generally in the 2 to 3 range. A synonym for chlorastrolite is
"greenstone", which bothers me as a geologist because geenstone
is also a name for any non-foliated low-grade metamorphic rock
consisting of mostly green minerals. Thus when you read in the
geological literature about "greenstone belts" those are not
large regions made of gemmy pumpellyite!

I recall being on a mine dump in the Keweenawan when some
rather neophyte-looking people drove up and started
searching for rocks. One of them picked up a rock, carried it
over to me, and asked me if, since that the rock was green, it
was a piece of copper. I said "Oh no, that's a chloastrolite".
As I was ready to tell him what a nice find he had made, he
said "Oh.", tossed the rock and walked away. A minute later
they were in their car and driving away. I am slightly
ashamed to admit, I picked then that rock up and put it in my
box. Caveat collector.

Have a great day - Dr. Bill

Dr. William S. Cordua
Professor of Geology/Mineralogy
University of Wisconsin - River Falls
River Falls, WI 54022
william.s.cordua@uwrf.edu
"Speak to the Earth and it shall teach thee" - Job 12:8"

Amy, having read the above, I would follow their advice and
not tumble it, but sand it with a Dremel or flex shaft tool,
carefully, and do the final polish with Zam. If you wish to
test whether it might be chlorite, you can use pure copper
as a scratch tool. Copper should scratch chlorite but not
scratch chlorastrolite.

Hope all of this helps. I know I learned a lot!

hale.)
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<MSG4>

Subject: NEW: Experiences in Cutting Opals


I've cut several pounds of opal over the years. I worked a
couple years for a jewelry store as a stonecutter (second job
and used my own equipment at home with their rough, great
deal!) and cut replacement opals for rings, and opals and
other stuff for their designers to work with. Let me offer
you a few tricks I learned about opals.

Opal is soft. It also tends to craze or scorch if it gets too
hot. Opal is hydrated silica. However, the silica is in the
form of very small balls. Think of a chunk of opal as a
laundry bag full of ping pong balls. When the balls are just
jumbled together, there is no orderly arrangement and you will
not have fire. When the balls get lined up into an arrangement,
like a crystal, you can have fire. The fire actually is a
diffraction effect, and flat planes of the balls are needed.

The balls also leave small wedge shaped cracks between them.
This gets filled with water (up to about 10%) and sometimes
other stuff (iron and aluminum are common, coloring the
matrix). The diffraction effect that gives the fire actually
comes from the orderly wedges of water between the balls. It
forms a diffraction grating. This water is also the cause of
the difficulties in polishing opal. Once it reaches 212
degrees F it turns to steam and the resulting pressure
fractures the rock.

Opals that are worn often can replace any lost moisture by
adsorbing water from the body and will retain their fire
longer than if they were left in a drawer. It takes years
before the effect is obvious. I personally store my opal rough
in water (as well as a few good cabs) and would think it is
preferred to glycerin or other substances suggested for
preserving opals.

Because of this you need lots of water feed, and don't bear
down hard on the wheel because that generates heat. I seldom
used a coarse wheel for grinding, starting about half way
thru the usual sequence (of 3 or 5 grits) and making sure the
finest grinding wheel left a smooth surface by lightening up
on the pressure on it a bit towards the end. Dress the wheels.

For sanding I preferred to use worn disks as new ones cut too
fast, especially those below 600 grade. I also preferred to
sand wet, using a dry disk and a spray bottle to moisten it
up. I concentrated my sanding on the finer grades, frequently
using only 600 and 1000 (or only 600 when well worn so it
made a good finish).

I found a hard felt wheel better than leather for polishing,
and usually used cerium oxide in a watery mixture which I
hand rubbed into the felt before starting the polisher
(horizontal lap). Most of the polish actually comes up in the
finest sanding with opals (and many other soft stones), so
don't overdo the polishing. Don't press any harder than
necessary to start feeling the polishing tugs from the lap,
and don't let it overheat. Keep a cup of water nearby to dip
the opal into often to help cool it off. Use a spray bottle
to make sure the felt does not dry out.

A lot of the opals I cut were small. Ordinary dop sticks get
to be a pain at those sizes. Take a number 6 finish nail and
smooth off/polish up the head on your find grinding wheel. Its
best of you leave a little of the nail-set dimple in the head
of the nail. A small drop of superglue on the polished surface
makes a great opal dop stick. Hold it on the rock until it
sets. Cut the stone. To remove, hold the stone between thumb
and finger firmly, with the nail end sticking out (but it
should be lightly supported by your finger/thumb that have
real pressure on the stone). Rap the nail sharply on the
metal edge of your grinder and it will pop off. Occasionally
some glue remains on the stone and you need to grind, or trim
it of with a knife, to get a clean back. I had a few rare
occasions where the back of the stone chipped. The biggest
advantage was speed.

Another trick is to rough grind the opal to shape (especially
when doing things like hearts or butterfly wing slabs), making
it a little large. Toss it in the tumbler with a bunch of
other shaped opals and a bunch of small gravel (or garnets,
which work great because they produce garnet fines as they
tumble which are a great finish abrasive) or trim saw scraps,
and run thru fine grinding and polishing while you do other
stuff. You can also fine grind on the wheel and do pre-polish
and polish in the tumbler. If you do a good job of keeping
the tumbler clean of previous grit sizes (watch out for poorly
graded or contaminated (by larger sizes) grits, which is
usually the cause of tumbling scratches) you can get a better
polish than by hand most of the time.

Opals are my favorite cutting stone. Now if I can just find
an endless supply of good rough for next to nothing...<grin>

Kreigh Tomaszewski
Kreigh <Tomaszew@Concentric.net>

non-commercial republish permission granted with attribution
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<MSG5>

Subject: NEW: How Do I Get Started?


Hale,

I'm just getting started into the field of lapidary, and have
lots of questions, I just haven't figured out what they are
yet!

I had a small tumbler years ago, and finally wore it out, and
haven't done anything since. My former employer decided that
after having 5 spinal surgeries, I wasn't much good to them
anymore, so now I'm retired and have a lot of time to do
whatever I feel like. I started reading Lapidary Journal a
couple of months back and find myself getting excited about
getting into lapidary again. I think that making jewelry,
primarily for my wife, is what I'd like to start with. But I
have very limited knowledge of gems and minerals. Can you
recommend a good book that will give a colored picture and
description of each type?

Also, do you have any suggestions for me that would help me
pursue my "new hobby?"

Thanks for your time and effort!

Regards,

Steve Shawn
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(Hale's Note: OK gang. lets give this guy some good advice.
You know the drill - gem clubs, shows, etc. So please answer
his questions and add your advice! hale)
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Subject: NEW: Fossicking Gemstones in Southern India


I am particularly interested in hearing from anyone who can
help me gather information upon this topic, as i am visiting
Tamil Nadu and Andrha Pradesh etc. in 3 months time.
Especially on quartz crystal, garnet etc., or any gems of
significance.

Mark. A. O'Brien
<mobrie11@scu.edu.au>
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<MSG7>

Subject: NEW: Cutting Cat's Eye Opal


HALLELUIAH! I am so glad to see you back, Hale! You asked
for questions to get started with, so here goes.

Does anyone out there have info on cutting the catseye opal
to get the best results? I am just about to start on my
first cut and if there are any pointers I could use them. I
have cut lots of fire opal, Mexican jelly, and Idaho stones
but am a little nervous about the catseye as I didn't get a
lot, and don't want to mess it up! I hate starting over!

Any help out there?

Sue

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Subject: NEW: Padparadscha


Hello Everyone!

I'm still puzzling over the proper color of Pads. I have a
small (3x5mm) stone that is more color change; pink/red
sometimes and pink/orange other times, depending on light and
angle.

My reference books show the stone as more pink; however one of
them (Schumann's "Gemstones of the world" pictures a yellow
Pad. A TV network displays their synthetic pads, and they look
orange, more like a Mexican Opal.

What is the correct color, and if a pad is supposed to be
pink/orange, how is it that Schumann's is yellow? Physical
properties?

Also, in rough, what does it look like?

I'm confused (nothing new, as you know <g>)!

Thanks!
Lorraine
<lclohan@email.msn.com>
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<MSG9>

Subject: NEW: Want Advice of Cabbing Set-up


Hi all, I was just wondering what all of you suggest as the
best lap/polishing media combination for general use. I am
getting geared up to do a large production run of primarily
quartz family material, and need to have a very durable
polishing pad and media for long term use on our cab unit.

Thanks in advance <just a stupid facetor...tee hee>

Paul Ahlstedt
<gemking@inland.net>
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Subject: NEW: Field Trip


Around the end of September, my wife and I will be taking a
vacation and travelling the east coast around the Blue Ridge,
from Virginia to Georgia. We'd love to find some spots where
we could either pick a few rocks or visit a few rock shops.

Our interests? Mostly cabbing, but we'll always look at
interesting specimens of anything. My wife is especially
fond of flourite crystals, especially those with multiple
colors or color bands. Me, I would like to work up to trying
star sapphires, but am interested in clear quartz and other
things. How's that for vague?

Any hints on places to go, possible rock shows, places
not_to_go, etc., would be greatly appreciated.


Thanks,

Bob and Pam Lombardi
<blombard@iu.net>


"non-commercial reproduction permitted"
-------------------------------------------------------------
(Hale's Note: Usually I don't include notes like this, but I
have a personal interest in this one! As you go through NC,
you will go near Franklin, which has gem shops and mines. By
law, the ones salted must be posted as such. Go to the Chamber
of Commerce and get their brochures. Have fun in our state!
Anyone else with advice? hale)
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Subject: NEW: Cleaning NC Corundum Question

Hi Folks!
Got a question I'm relaying to you for help. Jeff Perkins
<spark@penn.com> asked me:

"What is the proper way to clean the feldspar and mica off
raw sapphire without fracturing the stone ? I have quite a
few sapphires from the Pressley mine in Canton N.C., and
where I live in Warren, PA. there are no Lapidaries for
miles...can you give me some hints on equipment, procedure,
etc. on preparing sapphire for the cut ? I have one that is
as big as a golf ball, and about ten others that are as big
as a quarter...just don't know what to do with them...rock
tumbler isn't giving me proper results."

What advice would you give this gentleman?
Thanks!

Carol J. Bova
<bova@bovagems.com>
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Subject: RE: Want Experience Info on 'Ugly Duckling' Blade


When I read the ugly duckling blade post to my husband his
comment was,"Change the name of the game, pay the penalty."

If I remember right, a blade cooled by oil lasts three times
longer than a blade cooled by water. The effort involved in
enclosing your saw will probably pay off in the long run.
Blades that size are not cheap. I have seen oil saws
running outdoors at a well known rural western rock shop
with oil soaking into the ground around the saws. Wonder
how their water well is doing. That stuff will pollute soil
just as easily as service station pollution. Breathing oil
is no fun either. I have used an overhead oil cooled saw
without a mask and regretted it.

On the other hand, I was in a USGS lab several years ago,
before they built a new environmentally safe one. In order
to keep from contaminating specimens for chemical tests, the
saws all used water for lubricant. It was very obvious that
the dried out residue was dusting the shop, whereas with oil
it would have been held in the oil. No matter what you are
using for lubricant, it makes good sense to keep it enclosed
in the saw container.

Good health to you.

Rose McArthur
<obmcarthur@clearwater.net>

non commercial republishing rights granted
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<MSG13>

Subject: RE: Which Tumbler is Best?

I have found that the vibrating tumbler works best for me. I
have been using the Gy-Roc Vibrahone produced by Tagit Company
in San Juan Capistrano, Ca.

It is a bowl set-up and can be easily done "piggyback". I
have done up to 3 bowls at a time successfully. Their address
is P.O.Box 1534, San Juan Capistrano. Ca 92675
Phone: (714) 496-7742. Any questions, mail me -

Steve Ensor
(SEnsor9500@aol.com)
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Subject: RE: Turquoise Rough Prices

Prices on rough turquoise have gone way up and are now selling
by gram weight here in California. Usually around $2 to
$7/gram. Be very careful when you are buying Turquoise though,
much of it is now "stabilized", that is to say, it has been
heated and plastic has been infused into it to keep it from
breaking. The problem is, a lot of it has become more plastic
than rock; in some instances as high as 75% plastic. Another
thing to look out for is Chinese Turquoise in a pale green
color - it is very soft and chalky, absolutely useless for
lapidary work. The last from past bitter experience.

Good luck,

Steve Ensor
(SEnsor9500@aol.com)
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Subject: BIO: Duane Bolanowski

Hi,

I've been into rocks for a long time have a degree in geology
mostly stratigraphy and biology which is where I make my
living.

We have been in the lapidary business for about 2 years.
Mostly pre-made items until recently we have made same forays
into silversmithing and cabbing. We also sell minerals and
rough. The cabbing unit we have is a Diamond Pacific Pixie
also have an old old homemade slab saw. But it still works
well. Well that's about it. Hope to be able to participate in
this group eventually.

Thanks.

Duane
<Dbldb54@aol.com>
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<MSG16>

Subject: BIO: Kreigh Tomaszewski


I started collecting rocks and minerals as a pebble pup. When I was 7, I took lapidary classes at the Grand Rapids Public Museum. They were
jointly sponsored by the Grand Rapids Rock and Mineral Association, which sadly no longer exists (but there still are other local clubs).
Forty something years later I still collect, and the Grand Rapids Public
Museum has invited me back for a one day, one table, exhibit of some of
my collection as the 'Rocks and Minerals' part of an on-going
'Magnificant Obsessions - Collecting A to Z' series of exhibits. Nothing
spectacular, but if you're in Grand Rapids on December 12, 1998, stop
by the Museum to see at least a couple fine specimens. I'm using it to
boost rockhounding.

I also still cut. I have a Beacon Star 6" trim saw. I have a 5 wheel (3
grind, 1 sand - usually 320, 600, 1000, 1 polish or sand - usually
leather lap and cerium oxide) Beacon Star grinder. I have a Gemlap that
I use with a felt lap for polishing, and for sphere cutting (made my own
cutter dies, by drilling and tapping pipe plugs, and use carbo). I also
have several tumblers, which has been most of my recent activity due to
time constraints. I've cabbed a bit of just about anything over the
years and given most of it away (as just a cabbed stone). I took my
grinder to my kid's school one year for a day and polished a Petoskey
Stone for each kid, in the classroom, as they watched. I've never had so
much fun. I still go back annually to help teach about rocks, minerals,
and geology as a science unit.

I've cut several pounds of opal over the years. I worked a couple years
for a jewelry store as a stonecutter (second job and used my own equipment at home with their rough, great deal!) and cut replacement opals for rings, and opals and other stuff for their designers to work with. I am submitting a seperate post with more details. I am a computer (systems) programmer in my first job.

I look forward to learning more about lapidary from the members of this
list and hope I will be able to occasionally contribute something
useful.

Kreigh Tomaszewski
Kreigh <Tomaszew@Concentric.net>

non-commercial republish permission granted with attribution
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