mineral
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Hardness: 7 on Mohs scale; Color: purple to violet; Luster: vitreous (glassy); Crystal structure: hexagonal/trigonal; Cleavage: none (conchoidal fracture); Specific gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- purple to violet
- Luster
- vitreous (glassy)
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Physical properties
Hardness: 7 on Mohs scale; Color: purple to violet; Luster: vitreous (glassy); Crystal structure: hexagonal/trigonal; Cleavage: none (conchoidal fracture); Specific gravity: 2.65.
Formation & geological history
Formed in hydrothermal veins or as druzy linings in volcanic rock cavities (geodes). The purple color is caused by natural irradiation of trace iron impurities.
Uses & applications
Primarily used as a gemstone in jewelry (rings, necklaces), high-end interior decoration, and as a popular metaphysical or collector's specimen.
Geological facts
Amethyst was once considered one of the 'Cardinal gems' and was more valuable than diamonds until large deposits were discovered in Brazil in the 1700s.
Field identification & locations
Identify in the field by its distinct purple hue and prismatic crystals that lack cleavage. Common in Brazil, Uruguay, and Arizona.
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Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock
Granite
Granite (Phaneritic intrusive igneous rock)
igneous