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US Gemstones:
Origins & Uses
What constitutes a Gemstone?
"Gem, gemstone, or gem material are materials used for personal
adornment, display, or objects of art because they possess beauty, rarity,
and durability."
- There are three types of gemstones: natural, synthetic, and simulate.
- Natural gemstones include minerals and organic materials such as "amber,
coral, fossil ivory, mother of pearl, natural and cultured freshwater
pearls, and natural saltwater pearls."
- What the difference between synthetic and stimulant gemstones?
Synthetics are laboratory grown and have "the same appearance,
optical, physical, and chemical properties as the natural materials.
Simulants are laboratory grown materials but they only share the appearance
of gemstones, they do not have the rest of the properties of the natural
gems.
- The bulk of the gemstones mined in the U.S. fall under the following
categories: Chalcedony, Feldspar, Garnet, Opal, Pearls, Peridot, Quartz,
Sapphires, Tourmaline, Turquoise, and Collector or Specialty.
(back to top)
Chalcedony (You may not
know the word, but you know the stones)
Definition: Chalcedony is an umbrella term for "varieties of cryptocrystalline
quartz gemstones" which are found in all 50 U.S. states. The category
includes "carnelian, sard, plasma, prase, bloodstone, onyx, sardonyx,
chrysoprase, thundereggs, agate, flint, chert, jasper, petrified wood,
and petrified dinosaur bone."
- Aside from obsidian, Chalcedony was probably "the earliest raw
material" used by humans (along with "sticks, animal skins,
bones, plain rocks, and possibly obsidian.")
- Early human cultures made "points, knives, tools, cups and bowls"
from Chalcedony such as "agate, agatized coral, flint, jasper and
petrified wood." These materials slowly made the transition from
utilitarian to ornamental purposes.
- Alaskan agates are found in gravel pits and in stream and river beds
near the Yukon Territory, as well as on some beaches.
- Arizona is famous for its petrified wood because of Petrified Forest
National Park and because "petrified wood ranks third in value of
commercially produced gemstones."
- Petrified wood logs vary in size from a quarter inch to diameters
over five feet.
- Arizona petrified wood is used for: tumble polishing, baroque jewelry,
cabochons. Polished slabs are used in pen set bases and clock faces, bookends,
decorator pieces, carvings, and furniture.
- Florida has only one gemstone, silicified coral, which was first found
near Tampa Bay in 1825.
- Find yourself in Montana? Grayish-white moss agate is found in the
Yellowstone River.
- Oregon's state rock, the "thunderegg" comes from soft volcanic
ash beds.
- Looking for petrified palm wood specifically? You'll have to get it
from Texas.
- Washington state produces the most kinds of petrified wood: "redwood,
10 varieties of oak, cypress, elm, maple, willow, cedar, poplar, chestnut,
alder, birch, persimmon, laurel and ginkgo."
(back to top)
Collector or Specialty
Gemstones
What does this category mean? The category includes any "rare,
unusual, or unique gems that are not usually seen by the gem buying public,"
particularly due to size or color.
- Many of these stones are non-durable, that means they're too soft
and scratch, or are too brittle and shatter. Some stones are both soft
and fragile.
- Yellow and blue facet-grade opal comes from Idaho.
- The world's largest, faceted yellow fluorite was cut out of a mine
in Idaho.
"The world famous zinc deposits near Franklin in Sussex county
New Jersey produced gem-quality sphalerite, willemite, and zincite."
"Deposits in the Wah Wah Mountains and the Thomas Range Mountains
in Utah are the only known deposits in the world of fine-quality, bright
red facet-grade beryl."
Researched and written by Sylvie Beauvais, adapted from Gordon Austin,
"An Overview of Production of Specific U.S. Gemstones." Special
Publication 14-95. United States Department of the Interior, U.S. Bureau
of Mines, 1995. (back to top)
Feldspar (Moonstones, Sunstones,
and other colors)
What is it?
- Feldspar, aluminosilicate, is the most common of all the minerals in
the earth's crust. It plays a big role for industrial uses, helping in
the commercial production of "glass, plumbing fixtures, tiles, and
pottery."
What's it worth?
- In 1995, U.S. industry used 630,000 tons of feldspar, worth approximately
$27.4 million. This is only the part of feldspar's story in the US: this
mineral is also a gemstone, and its use as a gemstone is growing though
it remains a small portion of the market (production was worth $700,000
in 1993.)
The Feldspar family and two popular siblings
- Still think you've never seen or touched feldspar? Two well-known varieties
are sunstones and moonstones, which are known for their optical properties.
The feldspar family is complicated and diverse: it includes nine species,
varieties within species, and intergrowth of species-gems are found within
all these variants, but gem-quality feldspar overall is quite rare.
We've got the best, some of it
- India and Sri Lanka may be well known for the moonstones, but New Mexico's
Catron County produces adularia moonstones that are comparable in quality
to the best these foreign countries offer.
Do you love the blue moonstones? They're actually quite rare and only
account for 10% of the New Mexico stock. Do you love the color red? The
best gem-quality red labradorite, the official name for a sunstone, is
mined in Oregon. The fine coloring of sunstones comes from the "millions
of copper platelets that reflects the light." This play of color
is has its own German noun, it is called "schiller."
Like diversity?
- Oregon sunstone comes in many colors: "straw yellow [the most common
color], pink, peach, red, salmon red-orange, red-green, and blue-green."
Two and three colored stones exist, with combinations of yellow, red and
green.
Sunstone revolution
- In the sunstone universe, a revolution occurred in 1988 when the Ponderosa
Mine was discovered and it started producing the most beautiful sunstones
ever seen. "For the first time ever, there was a continuous U.S.
supply of the more desirable colors in most of the calibrated sizes up
to several carats needed by the jewelry industry." High-quality red
sunstones have been cut in size up to 10 carats.
Green Amazon
- There's another world-class feldspar gem found in America: green Amazonite
from Amelia County, Virginia. It is "deep, blue-green, translucent"
and it comes from either the Morefield or the Rutherford Mines. Morefield
mine operates as a commercial gemstone mine and a fee-for-mine. The Rutherford
mine opens one single weekend per year, allowing digging for a fee. One
weekend per year!
Researched and written by Sylvie Beauvais, adapted from Gordon Austin,
"An Overview of Production of Specific U.S. Gemstones." Special
Publication 14-95. United States Department of the Interior, U.S. Bureau
of Mines, 1995. (back to top)
Garnet
How did the January birthstone get its name?
- It's based on the Latin granatus, like a grain, because the crystals
"resemble grains or seeds embedded in the crystal matrix." Garnet
defines "a family of minerals having similar physical and crystalline
properties." The general chemical formula: A3B2(SiO4)3. Most of the
trade names for the stone relate to its color.
The Garnet Rainbow
- Hessonite means "fine orange, cinnamon brown, or pinkish grossularite."
- Tsavorite is "fine dark green grossularite."
- Melanite is black (has titanium), and demantoid is rich green (also
with titanium).
- Malaya varies from red to orange, brown, peach and pink.
- Rhodolite is purplish red.
- And the Bohemian garnet? A pyrope garnet from the Czech Republic.
Super Garnet
- You thought garnet=red, didn't you? Take heed, "garnet displays
the greatest variety of color of any mineral." A garnet can come
in any shade, except for blue. Feel free to surprise a January birthday
and find the not-red garnet that reminds you of them. Some garnets even
change color-depending on whether you see them in natural light versus
incandescent light.
The old and now new story of garnets
- Garnets were used as gemstones even in prehistoric times. We've brought
them into the industrial age. They were first used commercially for coated
sandpaper manufactured by Henry Hudson Barton in 1878. World industry
use has grown since Henry's time--110,000 tons were used in 1994. That
year, U.S. Industrial production was worth $14 million, while gem production
was a paltry $233,000 in comparison.
Beautiful name places
- In the US, Garnets are found in places with names such as these: Apache
County, Garnet Ridge, Buell Park, Stanley, (Arizona towns), Siskiyou County,
Traverse Creek, Watts Valley, Selma, Big Bar, and El Toro, Dos Cabezas,
Mesa Grande, Rincon and Pala Districts (California).
Researched and written by Sylvie Beauvais, adapted from Gordon Austin,
"An Overview of Production of Specific U.S. Gemstones." Special
Publication 14-95. United States Department of the Interior, U.S. Bureau
of Mines, 1995. (back to top)
Opal, a tricky beauty
"Opal is brittle, heat sensitive, and breaks and scratches easily;
additionally, some varieties self-destruct through the loss of water."
A quick read of the preceding shortcomings is a good reminder of the stone's
main virtue: its extraordinary beauty. The origins of the gem's name are
varied. It is supposed to have evolved from the Roman word opalus, derived
from the Greek works opallios ("to see a change of color"),
which in turn comes from the Sanskrit word for opal, upala, meaning precious
stone. All in all there's agreement here, the stone changes color, and
it is quite precious.
The story behind the name
- Beliefs come with all the names. The Greeks "thought that opals
gave their owners the powers of foresight and prophecy." Romans saw
hope and purity, and Arabs believed it fell from heaven. The nineteenth
century brought about the myth of opal being bad luck if it was not your
birthstone, this perception seems to be fading.
A big opal family, one well-known relative
"Opal has over one hundred variety and trade names, but the list
of commonly used names is much shorter." The famous opal is the "precious
opal" which is broken up into its shades: white, black, pink, and
blue-referring to the overall color, or body color, of the stone. Australia
produces the best grades of white and black opals, and Mexico has contributed
high-grade fire opals.
Stones go nuts too.
- When cracks develop along an opal's surface until they intersect, the
opal is "crazed." The cracking process is called crazing and
can cause the opal to shatter into "a crumbling sand-like material."
"Many museum pieces are crazed from the exposure to the air."
Researched and written by Sylvie Beauvais, adapted from Gordon Austin,
"An Overview of Production of Specific U.S. Gemstones." Special
Publication 14-95. United States Department of the Interior, U.S. Bureau
of Mines, 1995. (back to top)
Pearls
The Native Americans on the Atlantic coast and along the Mississippi
river collected and used freshwater mussel pearls and shells. Indian men
and women wore pearl pendants around the neck or ears and used the shell
to decorate clothes. A key difference from their salty cousins is that
freshwater pearls are not spherical, but are usually asymmetric in shape.
Though the shape may be irregular, there's a standardized vocabulary to
describe the recurring shapes: "rounds, pears, eggs, drops, buttons,
dome, and baroques." Baroques break into "nuggets, dog tooths,
wings, hammers, twins, barrels round-a-circle, and rosebuds."
How did you get that way?
- Unlike their seawater counterparts, freshwater pearls are often tinted,
and they have quite a range of colors: "white, silvery white, pink,
salmon, red copper, bronze, brown, lavender, purple, green, blue, cream,
and yellow." Pinks and lavenders are most popular for jewelry. Where
does the color come from? Blame the mussel. The color of the pearl is
related to the producing mussel's species, water quality, and where the
pearl lays in the shell.
From Art to Industry
- If you wish to find a pearl, you've got a lot of mussels to look at.
There are twenty different pearl-making mussel species out there. Where
does beauty come from? It arises from mussels with unlikely names: "the
ebony, washboard, hell-splitter, pimple back, elephant ear, mapleleaf,
three-ridge pigtoe, pistol grip, and the butterfly." Divers are on
the lookout for these species from April through September, all along
the rivers streams and lakes in the east, south, and central parts of
the U.S.
Commercial enterprises started in earnest in the U.S. as early as the
mid 1850s. Cultured freshwater pearl farms took longer to start up. The
first attempt was made by John Latendresse of Tennessee in 1963. (His
name roughly translates to "the tenderness" in French.) He became
the pioneer of the pearl cultivation industry in the US, opening five
farms over 30 years.
Researched and written by Sylvie Beauvais, adapted from Gordon Austin,
"An Overview of Production of Specific U.S. Gemstones." Special
Publication 14-95. United States Department of the Interior, U.S. Bureau
of Mines, 1995. (back to top)
Peridot
This yellow-green stone is the August birthstone. It's rumored to bring
good luck, peace, and success. Some historians believe that the emeralds
worn by Cleopatra were actually peridot. This is a common mistake. Upon
examination, many historical jewels with emerlads have turned out to be
covered in peridot.
Peridot has been part of the human experience for a long time. Johns
Island in the Red Sea was producing the stone as early as 70 A.D.. In
modern times, most of the peridot in the US comes from Arizona. The number
one locale for the production of the stone? Peridot Mesa is found on the
San Carlos Apache Indian Reservation in Gila County. It produces between
80% and 95% of world total. Individual Native Americans and families from
the reservation are the only people allowed to mine this deposit.
The two other countries with meaningful deposits and strong production
are China and Pakistan. Before the communist takeover, Myanmar used to
produce 20 to 40 carat high-end peridot.
Researched and written by Sylvie Beauvais, adapted from Gordon Austin,
"An Overview of Production of Specific U.S. Gemstones." Special
Publication 14-95. United States Department of the Interior, U.S. Bureau
of Mines, 1995. (back to top)
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