Amethyst
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Mineral NameAmethyst
Chemical FormulaSiO2
Mohs Hardness7
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.65
Colorspurple, violet, lilac
Transparencytransparent
Type LocalityBrazil, Uruguay, Zambia, Russia
Mineral GroupSilicates
Usesjewelry, ornamental, collector
Associated Mineralscalcite, zeolites, goethite, hematite
Raritycommon
Description
Amethyst is a purple variety of quartz, typically forming prismatic crystals within geodes or as druzy coatings. Its color ranges from pale lilac to deep violet.
Geological Context
Amethyst forms in hydrothermal veins and cavities (geodes) within igneous rocks, particularly basaltic lavas, and some metamorphic rocks. The purple color is attributed to irradiation of iron impurities within the quartz lattice.
