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Turquoise |
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Old European tradition associates
turquoise with horses. Turquoise supposedly protected horses
from all manner of ills, including drinking overly cold water
when overheated. The bearer of turquoise should be able to
resist evil and maintain virtue. Tibetans believe that
turquoise brings good fortune and health, and wards off the
evil eye. Turquoise was more valuable than gold to the Aztecs
of Mexico - a notion that was passed on to the conquering
Spaniards.
The name "turquoise" is fairly recent. Pliny
referred to it instead as callais, with comes form the Greek
kalos lithos meaning "beautiful stone." One who sees
the reflection of the new moon on turquoise will have good
luck, according to Persian legend. The Hindus thought a
similar combination would bring great wealth. And the Navajos
thought that a prayer spoken while throwing turquoise into the
river would bring rain.
Turquoise was thought to be amorphous until the first
crystalline specimens were found in 1911. Spiderweb turquoise
is veined with black matrix in a pattern that looks like
crocheted lace. Though often associated with Native Americans,
turquoise has been known globally since the Mesopotamians used
it by 5000 B.C. Turquoise may well have been the first
gemstone mined and the first imitated. The color of blue
turquoise can change under heat (about 500oF) to
greener hues. There are several minerals that make the dark
veins often found in turquoise. These include limonite,
sandstones, jaspers, and psilomelane. Veins of other colors
occur as well with minerals such as malachite and chrysocolla.
The name turquoise means Turkish, referring to the fact that
Europe's early turquoise got to Europe via Turkey. Avoid
contacting turquoise with body oils (or any oils, for that
matter). The stone is porous and will absorb oils causing the
color to yellow over time. The finest color is an intense
deep-blue azure, rarely seen. The intensity and evenness of
color are important valuation factors. So too is the quality
of the polish. "Robin's egg blue" is another highly
valued color.
Turquoise is found in Iran (Persian turquoise is of the
finest; it is Iran's national gemstone), Afghanistan,
Australia, China, Israel, Tanzania, Russia, Chile, Mexico,
Brazil, and the U.S. Folks who know their turquoise can tell
you what mine a particular specimen came from based on its
color and matrix pattern. The differences can be very subtle,
however, and the breadth of variation is enormous.
Treatments: Turquoise is often dyed to improve the
color. (It is very porous.) It may also be stabilized by a
polymer acting as a binder for the otherwise softer and more
porous natural material. This can be overdone, however, with
some materials called "turquoise" containing less
than 10% natural turquoise.
Imitators: Dyed chalcedony, dyed howlite, glasses,
ceramics, and plastics. Pieces of turquoise are pulverized and
reconstituted to look like natural turquoise. There are some
other minerals that can be confused with turquoise: amazonite,
chrysocolla, lazulite, hemamorphite, odontolite, serpentine,
smithsonite, faustite, prosopite, and variscite. Even the
early Egyptians imitated turquoise with a glazed quartz paste
(faience) due to the inferior quality of the available
turquoise. |
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