AmethystAmethyst is a purple variety of quartz often used as an ornament. The name comes
from the Greek a ("not") and methuskein ("to intoxicate"), a reference to the
belief that the stone protected its owner from drunkenness; the ancient Greeks
and Romans wore amethyst and made drinking vessels of it in the belief that it
would prevent intoxication.
Chemistry
Amethyst is the purple variety of quartz, its chemical formula is SiO2.
In the 20th century, the color of amethyst was attributed to the presence of
manganese. However, since it is capable of being greatly altered and even
discharged by heat, the color was believed by some authorities to be from an
organic source. Ferric thiocyanate was suggested, and sulfur was said to have
been detected in the mineral.
More recent work has shown that amethyst's coloration is due to ferric iron
impurities.Further study has shown a complex interplay of iron and aluminium is
responsible for the color.
On exposure to heat, amethyst generally becomes yellow, and much of the citrine,
cairngorm, or yellow quartz of jewelry is said to be merely "burnt amethyst."
Veins of amethystine quartz are apt to lose their color on the exposed outcrop.
Synthetic amethyst is made to imitate the best quality amethyst. Its chemical
and physical properties are so similar to that of natural amethyst that it
cannot be differentiated with absolute certainty without advanced gemological
testing (which is often cost prohibitive). There is one test (which is not 100
percent certain) based on "Brazil law twinning" (a form of quartz twinning where
right and left hand quartz structures are combined in a single crystal which can
be used to identify synthetic amethyst rather easily. In theory however it is
possible to create this material synthetically as well, but this type is not
available in large quantities in the market.
Composition
Amethyst is composed of an irregular superposition of alternate lamellae of
right-handed and left-handed quartz. It has been shown that this structure may
be due to mechanical stresses. As a consequence of this composite formation,
amethyst is apt to break with a rippled fracture or to show "thumb markings,"
and the intersection of two sets of curved ripples may produce on the fractured
surface a pattern something like that of "engine turning." Some mineralogists,
following Sir David Brewster, apply the name of amethyst to all quartz which
exhibits this structure, regardless of color.
Because it has a hardness of 7 on the Mohs scale, amethyst is treasured for its
use in jewelry. However, it is still just 1/15 as hard as diamond.
Amethyst in folklore and astrology
Amethyst is the birthstone associated with February. It is also associated with
the astrological signs of Pisces, Aries (especially the violet and purple
variety), Aquarius, and Sagittarius. It is a symbol of heavenly understanding,
and of the pioneer in thought and action on the philosophical, religious,
spiritual, and material planes. Ranking members of the Roman Catholic Church
traditionally wear rings set with a large amethyst as part of their office.
The Greek word "amethystos" (αμέθυστος) basically can be translated as "not
drunken." Amethyst
Jewellery was considered to be a strong antidote against drunkenness,
which is why wine goblets were often carved from it. Supposedly, when a drunken
Dionysus was pursuing a maiden called Amethystos, who refused his affections,
she prayed to the gods to remain chaste. The goddess Artemis granted the prayer,
transforming her into a white stone; humbled by Amethystos' desire to remain
chaste, Dionysus poured wine over the stone she had become as an offering, dying
the crystals purple.
Variants of the story include that Dionysus, the god of intoxication, had been
insulted by a mortal and swore revenge on the next mortal who crossed his path,
creating fierce tigers to carry out his wish; the mortal turned out to be a
beautiful young woman, Amethystos, who was on her way to pay tribute to Artemis.
Her life is spared by Artemis, who transforms the maiden into a statue of pure
crystalline quartz to protect her from the brutal claws. Dionysus wept tears of
wine in remorse for his action at the sight of the beautiful statue. The god's
tears stained the quartz purple. Another variation involves the goddess Rhea
presenting Dionysus with the amethyst stone to preserve the winedrinker's
sanity.
Geographic distribution
Amethyst occurs at many localities in the United States, but these specimens are
rarely fine enough for use in jewelry. Among these may be mentioned Amethyst
Mountain, Texas; Yellowstone National Park; Delaware County, Pennsylvania;
Haywood County, North Carolina; and Deer Hill and Stow, Maine. It is found also
in the Lake Superior region. Amethyst is relatively common in northwestern
Ontario, and in various locations throughout Nova Scotia, but uncommon elsewhere
in Canada. Amethyst is produced in abundance from the state of Minas Gerais in
Brazil where it occurs in large geodes within volcanic rocks. |
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