Stefan's Florilegium

lapidary-msg

lapidary-msg - 9/17/99

Period and SCA gemstone cutting.

NOTE: See also the files: gem-sources-msg, amber-msg, jewelry-msg, pearls-msg,
beads-msg, coronets-msg.

************************************************************************
NOTICE -

This file is a collection of various messages having a common theme that
I have collected from my reading of the various computer networks. Some
messages date back to 1989, some may be as recent as yesterday.

This file is part of a collection of files called Stefanšs Florilegium.
These files are available on the Internet at:
http://lg_photo.home.texas.net/florilegium/index.html

I have done a limited amount of editing. Messages having to do with
seperate topics were sometimes split into different files and sometimes
extraneous information was removed. For instance, the message IDs were
removed to save space and remove clutter.

The comments made in these messages are not necessarily my viewpoints. I
make no claims as to the accuracy of the information given by the
individual authors.

Please respect the time and efforts of those who have written these
messages. The copyright status of these messages is unclear at this
time. If information is published from these messages, please give
credit to the orignator(s).

Thank you,
Mark S. Harris AKA: Lord Stefan li Rous
RSVE60@email.sps.mot.com stefan@texas.net
************************************************************************

From: jjohns@tc3net.com
Newsgroups: rec.org.sca
Subject: Period lapidary techniques
Date: 19 Aug 1996 17:24:05 -0700

Does anyone know of sources for period lapidary techniques besides
Theophilus? His info is ok, but I'd like some alternatives to prepping rock
crystal by warming it in goat's blood - you get the idea. Any more practical
info would be most welcome. Thank you

Alasdair MacRaibert a'dun Alasdair
(Tom Johnson)
jjohns@tc3net.com

From: ddfr@aol.com (DDFr)
Newsgroups: rec.org.sca
Subject: Re: Period lapidary techniques
Date: 20 Aug 1996 14:23:03 -0400

Alasdair asks:
"Does anyone know of sources for period lapidary techniques besides
Theophilus? His info is ok, but I'd like some alternatives to prepping
rock crystal by warming it in goat's blood - you get the idea. Any more
practical info would be most welcome. Thank you"

1. You are unfair to Theophilus. He also describes practical techniques
for shaping and polishing stones, including the use of powdered emery,
attaching the stone to a dop stick with something rather like modern
dopping cement, etc.

2. Take a look also at Cellini's _Art of Goldsmithing and Sculpture_ or
something close to that title. He certainly discusses "improving" stones
by making colored foils to put behind them; I don't remember if there is
anything on actually cutting the stones.

David/Cariadoc

From: Alasdair MacRaibert
Newsgroups: rec.org.sca
Subject: Re: Period lapidary techniques
Date: 21 Aug 1996 19:18:58 -0700

In article , ddfr@aol.com says...
>1. You are unfair to Theophilus. He also describes practical techniques
>for shaping and polishing stones, including the use of powdered emery,
>attaching the stone to a dop stick with something rather like modern
>dopping cement, etc.

Your Grace Cariadoc, The reference to Theophilus was made as a poor joke.
When I read 'On Divers Arts', I made a joke with my lady on how they would
accept carving of rock crystal by his methods at a kingdom A&S competition
and whether it would be considered a science or a performing art. :-}
I do intend to try his recipe for chaser's pitch and his grinding techniques.

>2. Take a look also at Cellini's _Art of Goldsmithing and Sculpture_

Thank you for the reference and I will take a look at it the first chance I get.

I have two other possible references if you're interested. The first comes from
a Dover edition book called ' The Book Of Trades' which shows a series of wood
cuts published in 1568. One of the pictures is of a gem cutter using a treadle
powered rock grinder, but has no text description of methods.

The other reference is more empirical. In the July 1990 edition of National
Geographic, they have an article on emeralds. In that article they show a scene
from modern day India and a row of bow driven rock grinders in use. I would
assume that this design might be a predecessor to a treadle powered machine.

There seems to be very little research or period reference on the subject of
lapidary. If you should come across any other information, I would appreciate
the information.

Thank you, Alasdair MacRaibert/Tom Johnson

From: ddfr@aol.com (DDFr)
Newsgroups: rec.org.sca
Subject: Re: Period lapidary techniques
Date: 22 Aug 1996 22:13:42 -0400

On the subject of period lapidary techniques. All of the following is from
memory; I am travelling and my library is not.

1. I believe water driven wheels are recorded at Idar-Oberstein a little
before 1600.

2. Traditional Persian technology (not necessarily period) used a bow
driven lathe. So does modern Indian; I have one, although I have not used
it. So did classical technology, at least for gemstone carving. So I think
a bow driven lathe is a fair guess for period Islamic technology.

3. One question I do not know the answer to is whether the bow driven
lathe turned in one direction, with the operator raising or lowering the
bow to release the tension for strokes in the opposite direction (which
seems the obvious way to me), or whether it was reciprocating, which seems
to be the way that the somewhat similar spring lathe works.

4. Traditional Persian technique also uses a pump drill; I have seen it
done in Isfahan. I suspect that is period also, although I can't prove it.
It could be used for drilling and, perhaps, engraving gemstones.

5. You might want to look at my old article on gemstones, published long
ago in T.I. but also in the Miscellany that Elizabeth and I publish, which
is also accessible (minus the figures) on the web.

David/Cariadoc

From: zarazena@io.com (Vicki Marsh)
To: ansteorra@eden.com
Date: Wed, 30 Oct 1996 11:00:56 -0600 (CST)
Subject: Re: Good Enough? (Was Using

Sigrid Eiriksdottir wrote:
>I will do what I can for documentation at Laurel's prize tourney. Maybe
>someone there can point me to a reference or two.

Sigrid, do you have a public or university library nearby? When I live in
Austin, I know there were quite a few books in their libraries about
lapidary and jewelry, as I often did a lot of the research on jewelry-making
for my ex-husband. Also, some of the jewelry and lapidary shops will have
some books (like Dyers in Austin).

Sometimes, the How-to books are a place to start, as they often have some
history of the craft in the introduction. If so, look at their
bibliography/references, for the next place to look.

Keep looking
Zara Zina

From: afn03234@freenet2.afn.org (Ronald L. Charlotte)
Newsgroups: rec.org.sca
Subject: Re: Period Lapidary Sources...
Date: 2 Nov 1996 06:01:02 GMT

susankford@aol.com (SusanKFord) wrote:
> Does anyone have any books or other sources on period lapidary. I can do
> it with modern tools, but would like to know how it was done B>E>
> (before electricity...)

The one with the most useful information is _On Divers Arts_ by
Theophilus (ISBN 0 486 23784 2). It's widely available in Dover
reprint. Others include a smattering of info in _The Treatises of
Benvenuto Cellini on Goldsmithing and Sculpture_ (ISBN 0 486 21568 7).
There are a few others with small bits and pieces, and there is supposed
to be a Renaissance treatise on lapidary, but I've not found it yet.
--
al Thaalibi ---- An Crosaire, Trimaris
Ron Charlotte -- Gainesville, FL
afn03234@afn.org

From: william thomas powers <powers@cis.ohio-state.edu>
Subject: Re: Estrella Dust
To: markh@risc.sps.mot.com (Mark S. Harris)
Date: Sat, 22 Mar 1997 09:56:47 -0500 (EST)

> What's a "cab"? I'm assuming it is a cap of some type. I thought at
> first this was a mis-spelling but you wrote it this way several times.

Sorry, a bit of jargon there---"Cab" is short for "Cabochon" which is a
style of gem cutting. Instead of having flat facets the stone has a smooth
dome shape---much more a pre-renaissance cut for stones. In this case
the smooth domed quartz crystal provides a "window" to protect the item
in the reliquery but allow it to be seen. (There are several ways of mounting
them everything from soldering in a bezel to using an engraver to raise an
edge.

wilelm the smith

Date: Mon, 22 Feb 1999 10:37:54 -0600
From: Kathleen Keeler <kkeeler@unlinfo.unl.edu>
To: sca-arts@raven.cc.ukans.edu
Subject: Re: most usual semi-precious gems?

Anna Troy wrote:
> Well I've started to work on my circlet and I was planning on adding som
> small semi-precious carbochons. Which stones are no-no's for the 14th
> century? Were any more popular than the other or was it still the mish-mash
> that I've seen in earlier medieval work. I was planning on blue, red and
> maybe green stones depending on weither it will be 4 or more.
>
> Anna de Byxe

Modern stones are separated by chemistry--since in Period they didn't
have that tool, they mixed up some stones we distinguish: rubies and ruby-like
garnets were not separable, for example. Likewise, some
of the natural glasses and quartzes, when colored like emeralds (or other
stones) were mistaken. If there was faceting (ie if the precious gem had a
different number to faces than quartz) or hardness differences--they didn't
make mistakes.

See Cariadoc's Miscellany (online see SCA home page).

Avoid jade (not mentioned in Period lapidaries)

The Early English Text Society has a volume (#190, 1933) which reprints 7
Medieval English lapidaries. They are all based on Continental lapidaries,
are derivative and repetitious. Green stones mentioned in addition to
malachite include jasper, phrase, selenite, red include heliotrope, hyacinth,
sard. I'd characterize it as "lore of precious stones" but
it gives some sense of what stones they knew and used.

I did a composite translation of the information in the lapidaries- not so
much scholarly as entertaining, I understand a scholarly translation is in
progress -- from the very difficult English of the originals to modern
English. If you would like I can email you the text
(its maybe 10 typed pages.) The original is better, but much more difficult
to read and not very easily available (big university libraries and ILL).

Agnes deLanvallei, Mag Mor, Calontir

Date: Sat, 15 May 1999 21:34:50 -0700
From: Twcs <no1home@encompass.net>
To: sca-arts@raven.cc.ukans.edu
Subject: Re: Sunstone/Iceland Spar/Andalucite

<snip of modern mineral and gem info>

When is comes to equating a classical or medieval name of a rock
to a modern mineral, one needs to tread carefully. Nowadays, we
usually associate one mineral name to one distinct crystalline form
of an inorganic compound. For example, rhombahedral calcium
carbonate is calcite, whereas orthorhombic calcium carbonate is
aragonite. Aragonite is what pearls are made of, by the way.

In the middle ages, however, rock names were assigned on the
basis of physical properties, usually color and/or chemical action.
For example, both colorless topaz (Al2SiO4(F,OH)2) and diamond
would be called adamant. Similarly, the common hydrous sulfates
of iron, zinc and copper could all be used to make sulfuric acid,
and therefore were called green, white and blue vitriol respectively.
Alum is the worst, actually. Medievally, practically every white
hydroxenated or hydrous aluminum sulfate which occured naturally
and made a sweet-sour astingent solution when dissolved was
called and used as alum. There are over 20 modern minerals which
medievally were used as alum. (So if you've ever been confused
by medieval shipping records which differentiate between Egytpian
or Tuscan alum, know you know why...)

Unfortunately, threre's a great deal of confusion still concerning
the use of gem names. Yellow topaz is also called citrine, but so
is yellow quartz. Occasionally, yellow quartz is passed off as
topaz. Cat's eye, a variety of crysoberyl is often confused with
tiger's eye, a quartz replacement of fibrous crocidolite. There are
many more examples. The ones that really get me fired up are when
someone tells me about a "red sapphire" or a "blue emerald,"
especially in context of buying gems or jewellry. Sapphires are
by definition the blue variety of corundum, and emeralds are
the green variety of beryl. Red sapphires, blue emeralds and their
like are often either marketting ploys or cases of outright fraud.

Basically, correctly identifying a medieval rock name with a modern
mineral is a mess. I find it frustrating, and I do min id professionally.
I can't imagine what it must be like for folks who aren't rock geeks.
I'll give those who are interested a foot up, however: if you can find
a seventh or EARLIER edition of Dana's Manual of Mineralogy, you
will find that each mineral entry contains a history of what is was
named and by whom, including classical and medieval sources. The
early editions of Dana, however, are all nineteenth century, so they're
hard to find (try a university library - that's where the copy I use is
located). The Hoover and Hoover commentary to Argicola's De Re
Metallica is also helpful (it's included as part of their translation of
Agricola, and is available from Dover books).

ttfn, Twcs

Date: Fri, 21 May 1999 15:57:45 -0400
From: Warren & Meredith Harmon <ravenleaf@juno.com>
To: sca-arts@raven.cc.ukans.edu
Subject: Caro's List of Gem Books

Here is my recommended list of books - your mileage, of course, will
vary. Opinions expressed are only my own. I hope they help....

The Audubon Society Field Guide to North American Rocks and Minerals,
Charles W Chersterman, is a good field guide for those like me who like
to go digging in the field. The pictures are excellent, definitions,
locations, etc. It was my first rock/mineral book, and I consider it my
best book.

For a specification in gems, even though it's a little on the easy
side...Eyewiness Handbooks' Gemstones: The Visual Guide to More Than 130
Gemstone Varieties, by Cally Hall. ISBN 1-56458-498-4. This is the book
I carry when selling gems, because it can explain to almost everyone what
they are looking at...or what they may want. It's arranged by color
*and* composition, which is quite handy! Unfortunately, some of the
remarks are a bit generalistic for Scadians...I keep asking myself,
"yeah, I know the Egyptians used fluorite to carve scarabs, but how, why,
and what location did they get it from?!?" But *excellent* pictures of
faceted and carved and cabbed gems, with pics of some famous gems through
history.

For pictures alone, most of them period...Gemstones, published by
Streling Publishing Co, New York. Excellent shots of some of the more
exquisite jewelry pieces through history (one of these days I *will*
duplicate that Sumerian crown!!!). ISBN 0-8069-6834-6.

For those with a more chemical mind...Minerals and Gemstones of the
World, by G Brocardo. It's a Naturetrek Guide, ISBN 0-7153-0197-7. Each
mineral has a chemical analysis, but it's written with the layman in mind
(which I appreciate, even though I have a chemical background.)The charts
at the bottom of each page give a quick visual of the chemical properties
of each item...including clevage, hardness, color, mineral class,
specific gravity, fusibility, occurrence, luster, solubility, use,
preservation (which is great for display cases!) powder color, flame
color, toxicity, etc. Each overleaf can be folded so you can have a
side-by-side comparison with the page you're interested in. Excellent
stuff!

Now for those who are more interested in the metaphysical
properties...Love is in the Earth: A Kaleidoscope of Crystals Updated by
Melody. ISBN 0-9628190-3-4. Almost every rock, gem, and mineral known
to mankind is in here, but I have some caveats: 1) It's written as if you
actually know a little about mineralology, 2) You have to take one
person's word for what's written - it's difficult to corroborate
metaphysical info, 3) It doesn't use standardized names...black agate
from one location is given a different name than black agate from another
location. Of course, this ticks me off royally, but they at least
attempt to use location prefixes to the names...well, sometimes.... 4)
Some of these rocks you won't find outside someone's imagination.

And, here's my general caveat: whether or not you believe in the
metaphysical properties of rocks and minerals, please treat them as you
would any other medical item. Some people *will* have allergies, and
some people will *not* react as the book says. Please keep that in mind,
and treat people and rocks alike with respect and caution. Okay, my
lecture's over.

Also, for those thinking about getting into collecting or just want more
info: if yo uhave a Border's or a Barnes & Noble or a Feed & Read
Bookstore or...well, okay, you get the point - go and browse through
their rock & mineral section. You may find one that suits you quite
well, and you get to thumb through them yourself. That's what I did, and
I came up with these "gems" (heh!) on my own. But, good luck, and happy
hunting!

-Caro (herkimer hunting in four weeks!!!!)

Date: Tue, 25 May 1999 18:04:41 -0700 (PDT)
From: H B <nn3_shay@yahoo.com>
To: sca-arts@raven.cc.ukans.edu
Subject: Arab Roots of Gemology

In the current issue of _Gems & Gemology_, there is a book review of a
new English translation of _Best Thoughts on the Best of Stones_ by
Ahmad ibn Yusuf al Tifaschi (1184-1254), translated with comments by
Samar Najm Abul Huda, Scarecrow Press, Lanham, MD, 1998 US$45.00.
Review is excerpted here.

-- Harriet

"One important aspect of gemology is the history of gemstones.
Unfortunately, a wealth of early works have been lost to modern
gemologists, as evidenced by the number of gem references sited in
Pliny's first-century encyclopedia that have disappeared without a
trace. Although much of the knowledge possessed by ancient Greece and
Rome was preserved by Arabic writers, for the most part such works
remain inaccessible to all but the few western scholars who have
learned Arabic.

"This compilation offers a fascinating glimpse at ancient gemology,
according to the book _Best Thoughts on the Best of Stones_, by Ahmad
ibn Yusuf al Tifaschi (1184-1254). Its translation marks the first
time that early Arab gemological literature has been studied by a
modern Arab gemologist. Mrs. Huda is a competent translator who has
endeavored to make the contents of this pioneering work easily
accessible to English-speaking readers. She aimed the book at 'all
readers interested in gemology, mineralogy, jewelry, history, Arab
heritage, Islamic art, and the history of science.' In the reviewers'
opinion, she has accomplished her goals with great success...."

"...includes a glossary of gem names in English with their ancient and
modern Arabic names...places al Tifaschi's work in context by
describing the era in which he wrote and the nature of the Arabic
literature on gems from the eighth to the 13th centuries....explains
the monetary terms, weights, and measures employed at that time...."

"For each gemstone, al Tifaschi briefly describes how the gem is
formed; its localities, qualities, characteristics, benefits (mostly
medicinal and talismanic), and prices; and, in some cases, its lapidary
treatment...."

reviewed by Si and Ann Frazier, Lapidary Journal Correspondents

<the end>