mineral
Amethyst
Quartz (SiO2) with iron impurities
Hardness: 7 (Mohs), Color: light purple to violet, Luster: vitreous, Crystal structure: hexagonal/trigonal, Cleavage: none, Specific gravity: 2.65
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Physical properties
Hardness: 7 (Mohs), Color: light purple to violet, Luster: vitreous, Crystal structure: hexagonal/trigonal, Cleavage: none, Specific gravity: 2.65
Formation & geological history
Found within geodes or druzy clusters in volcanic rocks (basalt) or hydrothermal veins, formed after silica-rich solutions crystallize.
Uses & applications
Widely used in jewelry, as decorative display pieces, and in the metaphysical/gemstone collecting market.
Geological facts
The purple color is caused by natural irradiation and the presence of trace amounts of iron within the quartz structure. It was once considered as valuable as diamonds until large deposits were found in Brazil.
Field identification & locations
Identify by its distinct purple hue and quartz-like crystal habit. Common in Brazil, Uruguay, and Africa. Small tumbled or raw fragments are ubiquitous in gift shops.
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Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Sandstone with Mineral Veining or Crust
Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
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Schist
Schist
Metamorphic
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic