Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; hexagonal prisms with rhombohedral terminations
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2 (Silicon Dioxide) with trace amounts of iron (Fe3+) and irradiation
Formation Process
Hydrothermal; typically formed in cooling volcanic rock cavities (amygdules) or hydrothermal veins
About This Crystal
Transparent to translucent purple quartz. Colors range from pale lavender to deep royal purple with vitreous (glassy) luster. Often shows color zoning or white quartz matrix.
Physical Characteristics
Purple color; white streak; no cleavage; conchoidal fracture; 2.65 specific gravity; inert to weak fluorescence under UV.
Optical Properties
Refractive Index 1.544-1.553; Birefringence 0.009; No pleochroism; Doubly refractive (uniaxial positive).
Hardness & Durability
Origin Region
Notably Brazil, Uruguay, Madagascar, and Zambia; often found in basaltic geodes
Hardness & Durability
7 on the Mohs scale; good toughness; stable for daily jewelry wear but heat sensitive.
Care & Maintenance
Clean with warm soapy water (avoid ultrasonics if fractured); store away from sunlight to prevent color fading from UV exposure.
Rarity & Value
Common globally; value is determined by color intensity (deep Siberian purple is highest) and clarity; heat treatment is common to produce Citrine.
Special Characteristics
Color zoning (tiger stripes), occasional phantom inclusions, and negative crystals.
Lore & History
Historically used by Ancient Greeks to prevent intoxication; symbol of royalty and spiritual sobriety; associated with the Crown Chakra in crystal healing.