AMETHYST

Amethyst is the purple variety of the quartz mineral species. It’s the gem that’s most commonly associated with the color purple, even though there are other purple gems such as sapphire and tanzanite. Its purple color can be cool and bluish, or a reddish purple that’s sometimes referred to as “raspberry.

Most amethyst forms in clusters of protruding pyramidal crystals atop a basic matrix.  Frequently, spikes of amethyst crystals split off at their base, creating a Siamese twin appearance. In hydrothermal veins, amethyst often occurs in several growth phases, resulting in a banded, almost agate-like appearance. Amethyst also lines the inside of cavities and fissures in volcanic rocks, resulting in geodes and druzy crystal slabs. This druzy amethyst forms in short, stubby prismatic crystals often without distinguishable prism faces. Also deep within the earth, similar crystalline layers form within volcanic pipes, with striated bands and sometimes large scepter-like growths.  Amethyst scepters also form in medium-temperature alpine fissures and pegmatites. These typically form on top of other crystals, such as rock crystal or smoky quartz.

Some amethyst geodes, especially those mined in Brazil, are large enough for a person to stand inside of them! Naturally formed geodes take millions of years to form, and most geodes have been forming since prehistoric times.

BIRTHSTONES & ANNIVERSARIES

Amethyst is the birthstone for February and the gem for the 6th and 17th wedding anniversaries.

USES

Amethyst has a Mohs hardness of 7 and does not break by cleavage. That makes it durable enough for use in rings, bracelets, earrings, pendants, and any type of jewelry

MOHS HARDNESS

7

LUSTER

Vitreous

CHEMICAL COMPOUND

Amethyst is a variety of the mineral quartz and has the same chemical formula as quartz, which is SiO2. This means that amethyst is composed of silicon and oxygen, with each silicon atom bonded to four oxygen atoms in a tetrahedral arrangement.

WHERE TO FIND

Amethyst can be found in many locations around the world. Between 2000 and 2010, the greatest production was from Marabá and Pau d’Arco, Pará, and the Paraná Basin, Rio Grande do Sul, Brazil; Sandoval, Santa Cruz, Bolivia; Artigas, Uruguay; Kalomo, Zambia; and Thunder Bay, Ontario. Lesser amounts are found in many other locations in Africa, Brazil, Spain, Argentina, Russia, Afghanistan, South Korea, Mexico, and the United States.

DIAGNOSTIC PROPERTIES

Conchoidal fracture, glassy luster, hardness, purple color