Gems and Ornamental Stones
As I mentioned before we will be spending the next 3-6 weeks on
the sparklies - there is that much material
A: hears Semi moving into place for some "sparklies" to add to her
hoard
What I propose to do is start at the bottom with the Ornamental
and carving stones and move up to the precious gems and then the
imitations ,fakes and such any problems with that?
A: not a one DH
P: Not a one :>
P giggles "GMTA" :> -->
EW: works for us
Ok gems are simply stones that are used for decoration because
they are pretty :> Either for personal decoration or home
decoration They fall into 2 main groups - the
decorative/ornamental/carving stones and
the gems - there is a large area of overlap in the fancy or
cabochon stones however. Carving stones are (relatively) soft making
them easy to carve and polish - however this also means that they are
easy to scratch and mar. The real gems are generally harder making
them more wearable - especially those used to make things like rings.
In general we use quartz (H=7) as the dividing line between soft and
hard minerals as it is the most common mineral at the earth's
surface. Soft minerals are those that quartz scratches and hard are
those that scratch quartz :>
Ornamental Gemstones
Ornamental materials are those used to create objects larger than
jewelry but smaller than entire walls <G> . this includes inlay
materials, statuary and figurines, carved objects and containers as
well as any other items you might think of in that size range. In
reality essentially every kind of colored or pretty rock or massive
mineral has been used at least once. some of these materials are used
in construction and as polished facing stones also but we aren't
really considering them here - or at least we aren't considering such
uses
[G]: decorated frames around mirrors?
yep G <G>
*A* what about the mythic "amber wall"
[G]: noted
The carving stones fall into 4 main groups - the
Soft Stones, Organic
Materials, Medium Stones and the
Hard Stones.
Marble, alabaster (Gypsum) and soapstone (Serpentine) among others
being the soft stones - all have a hardness of 3 or less.
Soft Carving Stones
The main soft stones are: Alabaster, Serpentine, and
Marble, so lets look at them :>
Alabaster (and some onyx)
Is made from massive gypsum which has a hardness of 2 it normally
forms white materials with a visible graininess. That is the texture
that is desired - just large enough to be seen clearly without being
so big as to make carving difficult while it is normally white it can
be stained almost any color
[G]* is their another name for alabaster I can't find it in my
references.. the closest I get is albite -->
Its the name for massive gypsum G - check under that
[G]: gypsum specific gravity 2.3-2.4
right
Ok alabaster - is soft so its normally used for objects that
generally just sit and aren't subjected to wear and tear - or to
inexpensive objects
Serpentine (A.K.A. soapstone) - it forms generally green to
blue-green masses with other materials "marbled" in
[G]: serpi or serpen?
serpentine
[G]: thank-you
serpentine actually can range from a dull grey or blue to rich
greens
[G]: serpentine hardness 3-5 SG 2.5-2.6 monoclinic crystal
structure
There are a number of similar or related minerals that I'm
including under the heading serpentine - one of these is talc and as
they are often found mixed together we can sort of ignore the
differences for now
[Gh]: also nephrite..
NO NOT NEPHRITE G!
I'll get to nephrite later
[G]: ok sorry... similar species
not quite
Like the other soft stones serpentine is used for statuary,
figurines and decorative objects that aren't generally subject to
much handling and abrasion.
The last two major soft stones are both carbonates -
Marble and
Rhodocrosite.
Marble is recrystalized limestone and
dolomite. While it comes in a wide variety of colors and grain sizes
the best marbles are considered to be the white statuary marbles with
a "sugary" texture such as those found at Carrera Italy. Verde
Antique is a greenish marble with inclusions found at several places
in Italy and at Cardiff MD.
EW: sugary? I thought Marble was smooth?
Sugary because the grains are about the same size as those of
sugar grains son
EW: oh ok thanks :>
When polished smooth they provide much of the sparkle P. A
blue-white statuary marble is mined at Talledega AL and many other
varieties are found and named mostly according to the patterns seen
or colors or inclusions in them Marble deposits are found all along
the western edge of the Appalachian Mts and around most mountain
ranges world wide.
Among the minerals there are a number of other stones that are of low
hardness and often carved though most are not carved with the
frequency of those mentioned so far.
Rhodocrosite
is Manganese Carbonate and forms a pink banded massive rock that is
often turned int figurines or globes or other display objects.
Rhodocrosite is unusual in the soft stones in that it is often also
made into cabochon jewelry - this is because no other material has
its coloration really :> In general only the harder ornamental
stones are used to make jewelry for those who don't know - cabachons
are the flat or round toped generally opaque jewelry stones and for
this I'm including such other uses as beads as well. Some of the
better sites for Rhodocrosite are: Alma CO, S Africa (Hotazel) and
Argentina, (San Luis Catamarca Prov.)
Azurite
and
Malachite
are carbonates of copper with Azurite being Blue and Malachite
being green they are often found together and used together. While
they can form crystals they are normally found in massive bodies and
are often banded and intermixed in attractive patterns
They are also slightly harder than the other soft minerals (H:
3-4) and are used for jewelry and for a wide variety of objects from
chess pieces to balls to cups. In some cases they have even been used
to make columns and face walls (the Russian Winter Palace).
Sepiolite - better known as Meerschaum
EW: for pipes right?
Yes - It is white when first carved but absorbs tobacco juice and
skin oils turning it first golden and then a dark brown and
eventually black. I must have spent about 400-500$ on meerschaum
pipes when I was smoking. because they absorb the tobacco juices the
pipes produce a much milder flavor from the same tobacco - since you
don't get it on your tongue this way :> Actually lets say mellower
not milder.
T: where is meerschaum found?
T: in the wild that is?
The most important deposits are those at Esckischor Turkey, but
other deports are found in Spain, Greece, Czechoslovakia, Morocco,
and in Utah, California, Pennsylvania, and New Mexico.
G: and how difficult is it to carve?
As it has a hardness of 2.5 and is very finely granular its
actually fairly easy to carve - or to ruin <G>
T: I think I would like to give carving a try sometime.
G: I'd like to try as well
T: I am not very artistic but a pipe might be interesting to
make.
organic stones
There are 3 other soft ornamental materials but they are
effectively organic not mineral - Ivory,
Coral and Mother-of-Pearl
- of these only fossil ivory and M-o-P are legal to trade today -
though both coral and ivory are available :< Actually small
amounts of both are still legal and this is part of the trouble.
T: Is mop expensive?
T: I have a full 12" shell
just a sec T :>
Mother of Pearl is organically produced
aragonite plates - as such it is found in all shells so the general
price is fairly low however, such things as abalone shell and certain
other shell types (like Nautilus) that are rare or unusual are much
more expensive
T: but abalone is valued more cause ? ok
Mother of pearl is normally used as inlay or for things like
handles of knives or dinnerware since it forms in thin relatively
flat shapes
A: pearls are in another category?
Pearls are the same material - but! and so we will consider them
when we get to the precious gems where they have been classed
historically.
Coral - generally red or black in color it is
the dried colony of any of several varieties of medium to deep (15 to
100 Meters) sea corals . these corals form hard branching shapes and
it is these branches that are cut and polished to form beads and
jewelry or are carved or used as inlay .
Ivory is the teeth of several different
animals - elephants, whales (toothed), hippos, and Walrus or their
extinct predecessors like the mammoths
T: someone said elk had 2 Ivory teeth is this true?
welllllll your teeth are ivory technically. The thing that
separates the real ivory from the others is really the amount of
enamel and the overall size of the teeth :> yours aren't much good
for carving and figurines
T: cool.
EW: didn't George Washington have ivory false teeth?
yes and wood ones
T: ivory for dances and wood for every day he he he
EW: lol gee splinters
Today almost all trade in ivory is illegal - the only legal ivory
being fossil (mammoth) ivory and a little bit of legal ivory from
Burma and Africa where it is provided by the governments.
Unfortunately this provides a means of creating a black-market in the
stuff :< Ivory was once used for things like piano keys, pool
balls (especially the cueballs and for jewelry and many other items I
have an antique piccolo that has an ivory mouthpiece.
T: I seen a whale tooth with a early ship with sails drawn on it.
It was pretty cool but totally out of my price range.
Yes - such antique items are still available - sort of and there
are countries where you an buy ivory and other organic materials
legally - but exporting them to the US will get you in a world of
trouble.
Medium Carving stones
Chrysocolla
(hydrous copper-aluminum silicate) chrysacholla generally has a blue
to green color and is intermixed with other materials to create
interesting bandings
Variscite
(aluminum Phosphate) - variscite generally has a blue to green color
and may be intermixed with other materials to create interesting
bandings
the finely granular micas
P: Ohhhh, micas :>
Fuschite
- emerald green and rarely used made of chrome Muscovite
Alurgite - brick red - the manganese muscovite
Lepidolite
- the lithium mica that is a brilliant lilac color
Glauconite - a green marine mica may be used occasionally
also
Of these the most common by far is the lepidolite which is
generally left unpolished so the flakes show their colors
best
Other materials like the bright green nickel ore Garnierite
have been used on occasion but are much less frequent.
OK - next week we will look at the
Hard Ornamental
Stones
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