amethyst(redirected from Purple quartz)
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amethyst(ăm`əthĭst) [Gr.,=non-drunkenness], variety of quartzquartz,
one of the commonest of all rock-forming minerals and one of the most important constituents of the earth's crust. Chemically, it is silicon dioxide, SiO2.
..... Click the link for more information. , violet to purple in color, used as a gem. It is the most highly valued of the semiprecious quartzes. It is associated with a number of superstitions, being regarded as a love charm, as a potent influence in improving sleep, and as a protection against thieves and drunkenness. Brazil, Uruguay, Siberia, Sri Lanka, and parts of North America are important sources of supply. The so-called Oriental amethyst, or purple sapphire, is not quartz but a variety of corundum, a much harder and rarer stone.
a mineral, a violet or sky blue-violet variety of quartz (SiO2). On heating to 300–350°C, amethyst becomes yellow or is discharged. Decolorized amethyst reacquires its color after exposure to X rays. The mineral occurs in quartz veins, granitic rocks, amygdules of volcanic rocks, and sometimes in sedimentary rocks, such as silicon salts. The best specimens are used for jewelry and as ornamental stones. Especially fine are amethysts from the Urals and Brazil. A blue-violet variety of corundum is known in the jeweler’s craft as eastern amethyst.