mineral
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Hardness: 7 on Mohs scale; Color: light to deep purple; Luster: vitreous; Crystal structure: hexagonal; Cleavage: none; Specific gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- light to deep purple
- Luster
- vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: light to deep purple; Luster: vitreous; Crystal structure: hexagonal; Cleavage: none; Specific gravity: 2.65
Formation & geological history
Formed in igneous or metamorphic environments when silica-rich fluids fill cavities (geodes) or veins. The purple color results from irradiation of iron impurities within the quartz crystal lattice.
Uses & applications
Primarily used as a gemstone in jewelry, decorative carvings, and for metaphysical collecting.
Geological facts
Until the 18th century, amethyst was included in the cardinal gemstones on par with diamonds and rubies. It is the birthstone for February.
Field identification & locations
Identify by its characteristic purple color and standard quartz hardness (it will scratch glass). Often found in Brazil, Uruguay, and Zambia.
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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
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock