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. 40
2. Printing problem
3. RE: What is "Sunstone"
4. RE: What is "Sunstone"
5. RE: Polishing Intarsia
6. RE: Dangers of Rock Dust

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<MSG1>
Subject: LapDigest News for Issue No. 39

The next Digest will be published on Thursday or Friday of this week, as we have to go out of town for a day or so.

If you have queries about hardness of materials or density or specific gravity, please send them in now. We will start running the paper on hardness when we resume.

.. and wear safety glasses and a mask when needed; let's make lapidary safe AND fun!

hale
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<MSG2>
Subject: printing problem

Hale,
I am also having printing problems. I'm using a Dell Pentium computer and print on a Cannon BJC-610 using the print icon in Netscape Mail.
Larry Berger
lberger@planet.net
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<MSG3>
Subject: RE: What is "Sunstone"


<<I bought four interesting cabs at a jewelry show that the seller said were "sun stone." Does anyone know what this is? Is it rock/plastic? Is it natural/treated?
--Kathi Parker>>

Dear Kathi,
Sunstone is a feldspar. Hardness 6 to 6 1/2. It can be red, copper colored, nearly clear or green. It is found in the western U.S., where the minute copper inclusions give it its sparkle and color. I've seen great pieces from India too. Canada, South Norway and Russia are also sources. It can be confused with aventurine or glass.

Cathy
bodhi@his.com
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We have found Sun Stone in Oregon, which is a form of feldspar and also have seen it come from Madagascar (Species not remembered). You didn't give a description, so that would be helpful, but both forms are natural. The Oregon Sun Stone is untreated, but not sure about the Madagascar material.

Yours,

Susan Sanders
Jupchild45@aol.com
http://members.aol.com/jupchild45
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Sun stone is a microcline, aventurescent labradorite, or oligoclase feldspar. Hardness: 6 to 6.5 Found in several states but best material I have seen came from Oregon. Subject to cleavage, use care when setting.

Dick Friesen
friesenr@ix.netcom.com
-- non-commercial republish permission granted --
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<MSG4>

Subject: RE: What is "Sunstone"


Hale- I don't know if this is the sunstone that the inquiry was about. It
ran recently (maybe last year?) in the Rockfinder, our newsletter in South
Bend. Credit from another newsletter at the end. Herb

CORDIERITE - SUNSTONE OF THE VIKINGS?

The mineral cordierite is thought to be the source of the famous sunstone of the Vikings, who in the ninth century were expert navigators. Without benefit of compass, Viking sailors managed to ply their watery routes of conquest and commerce, navigating by the stars at night and the sun during the day. No matter what the weather, according to ancient Scandinavian sagas, the sun could be located with the aid of the magical "Sun Stone." Summarizing sunstone lore in a recent article in the archaeology magazine Skalk, Danish archaeologist Thorkild Ramskau lamented that none of the sagas clearly describe the sun stone. "But there seems to be a possibility," he wrote, "that it was aninstrument which in cloudy weather would showwhere the sun was." Now, with a clue supplied by a young archaeology enthusiast, Ramskau has discovered the secret of the sun-seeking stone of the ancients.

To the 10-year-old son of Jorgen Jensen, chief navigator of the Scandinavian Airline System, the instrument described in Skalk sounded like the twilight compass used by his father at higher latitudes, where the magnetic compass is unreliable. The twilight compass is equipped with a polarizing filter that enables a navigator to locate the sun-- even when it is behind the clouds or below the horizon--by the light polarized by the atmosphere. Intrigued by his son's observation, Jensen passed it on to Ramskau, who immediately recognized its scientific implications. Enlisting the aid of Denmark's Royal Court jeweler, the archaeologist collected minerals found in Scandinavia whose molecules are aligned parallel to each other just as the crystals are in a polarizing filter. Ramskau found that one of these minerals, a transparent crystal called cordierite, turned gray to violet-blue whenever its natural molecular alignment was held at right angles to the plane of polarized light f!
rom the sun. Thus, he reasoned, a Viking could have located the sun by rotating a chunk of cordierite until it turned blue.

Putting cordierite to the test, Ramskau accompanied navigator Jensen on a flight to Greenland, keeping track of the sun with his stone while Jensen used the twilight compass. His observations were accurate within 2.5 degrees of the sun's true position, and he was able to track the sun until it dipped 7 degrees below the horizon.

"I now feel convinced," Ramskau concludes, "that the old Vikings, with the aid of their sun stones, could navigate with enormous accuracy."

Herb Luckert
221 Marquette Ave
South Bend, IN 46617
219-282-1354
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(Ed. Note: Cordierite or Iolite is a brittle, transparent to translucent, magnesium-iron aluminum silicate. Large crystals occur in Norway. It is not the same as the mineral named 'sunstone', which is a feldspar material. But this is so fascinating, I had to include it here. Hope you enjoy it as much as did I!
hale)
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<MSG5>
Subject: RE: Polishing Intarsia


<<Is there an easy way to polish intarsia made out of material with wildly different hardnesses ? >>

[Why not polish your variously hard slabs separately first, then cut them out and build the intarsia polished-side-down on a dead-flat surface like a piece of plate glass? If you support the glass on blocks, you can peek underneath to see how it looks. When the piece is complete, you can apply mortar and reinforcement to the back to get a slab of concrete with the intarsia adhered to one side.]

Andrew Werby - United Artworks
Sculpture, Jewelry, and Other Art Stuff
drewid@lanminds.com
http://users.lanminds.com/~drewid
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<MSG6>
Subject: RE: Dangers of Rock Dust

Howdy Folks,
I would like to know if there exists the same huge difference in lung problems comparing smokers versus non-smokers with respect to 'rock dust' as there is with asbestos. My Dad lost about 1/3 of a lung and suffered other problems but in reading about the issue it appears that, he having been a smoker, his 'cilia' were coated with tar and particles cannot be removed from the lungs. If this is true it would be even MORE prudent for those of you who smoke to wear a mask.

(BTW-I too experience the 'scroll sideways' problem. DX2-50 running Netscape Nav. under 3.1)

Carl
1 Lucky Texan
alckytxn@flash.net
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