{{Otheruses}}

{{Infobox mineral
| name = '''Quartz'''
| category = Mineral variety
| boxwidth =
| boxbgcolor =
| image = Amethyst Quartz Macro 1.JPG
| imagesize =
| caption =
| formula = [[Silica]] (silicon dioxide, SiO₂)
| molweight =
| color = purple
| habit = 6-sided prism ending in 6-sided pyramid (typical)
| system = [[rhombohedral]] class 32
| twinning = Dauphine law, Brazil law and Japan law
| cleavage = None
| fracture = Conchoidal
| mohs = 7 - lower in impure varieties
| luster = Vitreous/glossy
| refractive = nω = 1.543 - 1.553 nε = 1.552 - 1.554
| opticalprop = Uniaxial (+) (Positive)
| birefringence = +0.009 (B-G interval)
| pleochroism = None
| streak = White
| gravity = 2.65 constant; variable in impure varieties
| density =
| melt = 1650 (±75) °C
| fusibility =
| diagnostic =
| solubility = H₂O insoluble
| diaphaneity = Transparent to translucent
| other = Piezoelectric
}}

'''Amethyst''' is a purple variety of [[quartz]] often used as an [[ornamental stone|ornament]]. The name comes from the [[Greek language|Greek]] ''a'' ("not") and ''methustos'' ("to intoxicate"), a reference to the belief that the stone protected its owner from [[drunkenness]]; the [[Ancient Greece|ancient Greeks]] and [[Ancient Rome|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. [[Iron|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.<ref>Klein, Cornelis and Hurlbut, Cornelius S., 1985 ''Manual of Mineralogy (after JD Dana)'' 20th edition, p. 441, John Wiley & Sons, New York</ref> Further study has shown a complex interplay of [[iron]] and [[aluminium]] is responsible for the color.<ref>Cohen, Alvin J., 1985, ''Amethyst color in quartz,the result of radiation protection involving iron', American Mineralogist, V. 70, pp 1180-1185</ref>

On exposure to heat, amethyst generally becomes [[yellow]], and much of the [[citrine]], [[Cairngorm (mineral)|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 {{Fact|date=March 2007}}.

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 [[Crystal twinning|quartz twinning]] where right and left hand quartz structures are combined in a single crystal<ref>{{cite web | url = http://www.quartzpage.de/crs_twins.html | title = Quartz Page Twinning Crystals | accessdate = 2007-05-28 }}</ref> 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.<ref name = "WiseSecrets1" />

==Composition==

Amethyst is composed of an irregular superposition of alternate [[lamellar structure|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 of hardness|Mohs scale]], amethyst is treasured for its use in jewelry.
[[Image:Amethystvb.jpg|thumb|250px|right|A polished amethyst gem stone.]]

==Hue and Tone==
Amethyst occurs in a continuum of primary hues from a light slightly pinkish violet to a deep grape purple. Amethyst may exhibit one or both secondary hues, red and/or blue. The ideal grade is called "Deep Siberian" and has a primary purple hue of around 75 - 80 percent, 15-20 percent blue and (depending on the light source) red secondary hues.<ref name="WiseSecrets1">''Secrets of the Gem Trade; The Connoisseur's Guide to Precious Gemstones'' Richard W Wise, Brunswick House Press, Lenox, Massachutes., 2003</ref>

==History==
Amethyst was used as a [[gemstone]] by the ancient [[Egypt]]ians and was largely employed in antiquity for [[intaglio (jewelry)|intaglio]]s. Beads of amethyst are found in [[Anglo-Saxons|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 [[crystal]]s occur either in the cavities of mineral-veins and in [[granite|granitic]] rocks, or as a lining in [[agate]] [[geode]]s. A huge geode, or "amethyst-grotto," from near Santa Cruz in southern [[Brazil]] was exhibited at the [[Düsseldorf, Germany]] Exhibition of [[1902]]. Many of the hollow agates of Brazil and [[Uruguay]] contain a crop of amethyst crystals in the interior. Much fine amethyst comes from [[Russia]], especially from near Mursinka in the [[Ekaterinburg]] district, where it occurs in drusy cavities in granitic rocks. Many localities in [[India]] yield amethyst.
[[Image:Quartz Amethyst.jpg|Museum-quality piece of Amethyst|thumb|250px]]

==Alternate terminology==

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 (usually the least-sought color). 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]]. In more recent times, certain gems (usually of Bolivian origin) that have shown alternate bands of amethyst purple with citrine orange have been given the name [[ametrine]].
Purple [[corundum]], or [[sapphire]] of amethystine tint, is called Oriental amethyst, but this expression is often applied by jewelers to fine examples of the ordinary amethystine quartz, even when not derived from eastern sources. Professional gemological associations, such as the [[Gemological Institute of America]] (GIA) or the [[American Gemological Society]] (AGS), discourage the use of the term "Oriental amethyst" to describe any gem, as it may be misleading.

The Second Book of Pseudo-Albertus Magnus, ''Of the Vertues of Certaine Stones'', refers to amethysts by the name ''Amarictus''.
[[Image:Srr046a.jpg|6 carat (1.2 g) pear shape amethyst ring|thumb]]
==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]]; 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 [[geode]]s within [[volcanic rock]]s. It is also found and mined in [[South Korea]]. The largest opencast amethyst vein in the world is in Maissau, Lower Austria.

==Value==
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]]. The highest grade Amethyst (called "Deep Russian") is exceptionally rare and therefore its value is dependent on the demand of collectors when one is found. It is however still orders of magnitude lower than the highest grade sapphires or rubies (Padparadscha Sapphire or "Pigeon Blood" Ruby) which can go for as much as $50,000 or more per carat.<ref name=WiseSecrets1> </ref>

Amethyst such as the "Russian" quality (bluish purple key color) and such as material recently found in Georgia since 2005 (with some of the stones showing both blue hue and red flashes) and of which its top material is considered of the best quality presently available <ref>{{cite journal | last = Bowling| first=Ryan L| title=Jackson Crossroads Amethyst Deposit, Wilkes County, Georgia | journal=Mineralogical Record A| volume=36 |issue=6| pages=479(8)|date=2005| accessdate = 2007-05-27 }}</ref> still command prices of not more than $50 per carat.<ref>Mountain Gems and Minerals, Little Switzerland, NC; one of the authors or Mineralogical Record and other articles and co-owner of the mine. Tucson showreport images: http://www.gamineral.org/t05-clarion_hotel.html </ref>

==Amethyst in folklore and astrology==
Amethyst is the [[birthstone]] associated with February. It is also associated with the [[astrological sign]]s of [[Pisces (astrology)|Pisces]], [[Aries (astrology)|Aries]] (especially the violet and purple variety), [[Aquarius (astrology)|Aquarius]], and [[Sagittarius (astrology)|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 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, dyeing 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.<ref>[http://www.gemstone.org/gem-by-gem/english/amethyst.html source]</ref> Another variation involves the goddess [[Rhea (mythology)|Rhea]] presenting Dionysus with the amethyst stone to preserve the winedrinker's sanity.<ref>(Nonnus, ''Dionysiaca,'' XII.380)</ref>

==See also==
{{Commons|Amethyst}}
*[[List of minerals]]
{{clear}}

== Notes ==
<references/>

== References ==
{{1911}}

*{{cite web |url=http://www.blm.gov/ak/jrmic/poster/amethyst.html |title=Amethyst |work=part of a poster by the Juneau – John Rishel Mineral Information Center |publisher=Alaska office of the United States Bureau of Land Management|accessdate=2006-09-11}}
*{{cite book |title=A Dictionary of Chemistry |publisher=Printed for Thomas Tegg, (et al.) |first=Andrew |last=Ure |year=1827 |url=http://books.google.com/books?vid=OCLC22415868&id=9YS0XNQU8x4C&pg=PA141&lpg=PA141&dq=Amethyst&as_brr=1 |accessdate=2006-09-11 |page=141 |quote=The amethyst is a gem of a violet colour, and great brilliancy, said to be as hard as the ruby or sapphire, from which it only differs in colour. This is called the oriental amethyst, and is very rare. When it inclines to the purple or rosy colour, it is more esteemed than when it is nearer to the blue. These amethysts have the same figure, hardness, specific gravity, and other qualities, as the best sapphires or rubies, and come from the same places, particularly from Persia, Arabia, Armenia and the West Indies. The occidental amethysts are merely coloured crystal or quartz.}}
*http://mineral.galleries.com/minerals/gemstone/amethyst/amethyst.htm
*http://www.mindat.org/min-198.html
*http://www.gemstone.org/gem-by-gem/english/amethyst.html

{{Jewellery Materials}}
{{Gems & Crystals}}

[[Category:Gemstones]]
[[Category:Quartz varieties]]
[[Category:Provincial symbols of Ontario]]

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