Geology Home Page physical geology historical geology planetary gems
Roger Weller, geology instructor
Amethyst (SiO2) is a mauve or purple variety of quartz often used as an embellishment. 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.
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. The purple color of amethyst is actually due to small amounts (approximately 40 parts per million) of iron (Fe4+) impurities at specific sites in the crystal structure of quartz.
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". 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 was used as a gemstone by the ancient Egyptians and was largely employed in antiquity for intaglios. Beads of amethyst are found in Anglo-Saxon graves in England. It is a widely distributed mineral, but fine, clear specimens that are suitable for cutting as ornamental stones are confined to comparatively few localities. Such crystals occur either in the cavities of mineral-veins and in granitic rocks, or as a lining in agate geodes.
Much fine amethyst comes from Russia, especially from near Mursinka in the Ekaterinburg district. Many localities in India yield amethyst; and it is found also in Sri Lanka, chiefly as pebbles. Due to its popularity as a gemstone, several descriptive terms have been coined in the gem trade to describe the varying colors of amethyst. "Rose de France" is usually a pale pinkish lavender or lilac shade. The most prized color is an intense violet with red flashes and is called "Siberian", although gems of this color may occur from several locations other than Siberia, notably Uruguay and Zambia. 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 district. Amethyst is relatively common in northwestern Ontario, but uncommon elsewhere in Canada; it was selected as the provincial mineral of Ontario in 1975.
Traditionally included in the cardinal, or most valuable, gemstones (along with diamond, sapphire, ruby and emerald), amethyst has lost much of its value due to the discovery of extensive deposits in locations such as Brazil.
Amethyst is the
associated with February. It is also associated with the
(especially the violet and purple variety),
It is a symbol of heavenly understanding, and of the pioneer in thought and
action on the philosophical, religious, spiritual and material planes. The Greek
word "amethystos" basically can be translated as "not drunken." Amethyst was
considered to be a strong antidote against drunkenness, which is why wine
goblets were often carved from it. Supposedly, when a drunken
pursuing a maiden called Amethystos, who refused his affections, she prayed to
the gods to remain chaste. The goddess
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. Or: "The legend of the origin of
amethyst comes from Greek myths. Dionysius, the god of intoxication, was angered
one day by an insult from a mere mortal and swore revenge on the next mortal
that crossed his path, creating fierce tigers to carry out his wish. Along came
unsuspecting Amethyst, a beautiful young maiden on her way to pay tribute to the
goddess Diana. Diana turned Amethyst into a stature 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, creating the gem we know today."