GO 340 Gemstones & Gemology
ES 567 Gemstones of the World
Dr. Susan Ward Aber, Geologist & Gemologist
Emporia State University
Emporia, Kansas USA

academic.emporia.edu/abersusa/go340/amethyst.htm

Amethyst


Rough amethyst.
Image taken from
the former Gallery of Gems.
Amethyst is a purple, crystalline variety, of quartz, SiO2. It has a hardness of 7 and average specific gravity at 2.65. The fracture is conchoidal and there is no cleavage. Amethyst is doubly refractive, 1.54 and 1.55, with weak to no fluorescence and pleochroism. Amethyst is in the trigonal/hexagonal crystal system which is reflected in the long prismatic, hexagonal-shaped crystal form, often with a six-sided pyramidal terminations on one end. Amethyst may be found in alluvial deposits, lining volcanic cavities, or metamorphic rock fissures.

According to Schumann (2011), amethyst imitations are beryl, fluorite, kunzite, spinel, topaz, tourmaline, and tinted glass (p. 134). Heating amethyst can a yellow to deep orange quartz termed citrine or a pale green quartz, called prasiolite (Schumann, p. 136).


Amethyst and White
Sapphire. Image taken
from the former Gallery of Gems.


Image taken from
Gem Hut.
Important amethyst deposits come from Brazil, Uruguay, Russia, Madagascar, Zambia, Namibia, Myanmar, India, Sri Lanka, Canada, and Mexico. Amethyst quality is sometimes referred to as Siberian, Uruguayan or Bahian, for high, medium, and low grades, regardless of the mineral deposit's source area. (Amethyst Mineral Galleries, 1995-2012). Amethyst source areas can be discerned by the colors (deep purple with red flashes is the most valued), color distribution, crystal shape of the rough material.
Amethyst from the Ural Mountains of Russia is a dark purple with good clarity; amethyst from Uruguay is medium to dark purple found in a druse habit lining volcanic vug or cavities; and amethyst from Bahia, Brazil also forms in druse habit with a light to medium color, with the darkest color at the tips of the crystals (Amethyst Mineral Galleries, 1995-2012). Amethyst may be layered with milky quartz or found bicolored, yellow and purple, and referred to as ametrine (Schumann, 2011, p. 118).
Image taken from
Gem Hut.

Image taken from
Gem Hut.
Amethyst is the birthstone for February and the sixth anniversary stone (Jewelry Central). The word, amethyst, comes from Greek, meaning not drunken and therefore gem lore perpetuated the belief that this stone would protect the wearer from drunkenness. Amethyst has a rich history and lore, from Diana transforming the maiden Amethyst into stone to this gem being one of the twelve stones in the breastplate of Aaron, the high priest of the Hebrews. Amethyst was identified with a prophet from one of the twelve tribes of Israel, who had the gift of tongues (CW Jewelers, 1999). Also, it is believed to treat headaches, sciatica, and pancreatic conditions (Schumann, 2011, p. 190).
It has been a favorite of royalty and religious leaders also. As it became more abundant, the price was lowered and it became popular with jewelry artists. Amethyst's popularity in combination with the fact that fine amethyst has become increasingly rare, has created the market for gem enhancement and synthesizing. It may be faceted, fashioned en cabochon or carved. Amethyst is found in the British Crown Jewels, a favorite of Catherine the Great, and considered to be sacred to Buddha in Tibet (Jewelry Central, 2000).
Image taken from
Jewelry Central.


References

Suggested Sites to Visit

Return to the Syllabus or choose another gemstone below.

Alexandrite Amber Amethyst Chalcedony Diamond Emerald
Garnet Jade Malachite Opal Pearl Peridot
Ruby Sapphire Tanzanite Topaz Tourmaline Turquoise

This page originates from the Earth Science department for the use and benefit of students enrolled at Emporia State University. For more information contact the course instructor, S. W. Aber, e-mail: esu.abersusie@gmail.com Thanks for visiting! Webpage created: November 15, 2000; last update: November 19, 2012.

Copyright 1999-2012 Susan Ward Aber. All rights reserved.