Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal; typically hexagona-prism habits with rhombohedral terminations
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2 (Silicon Dioxide) with trace amounts of Iron (Fe3+)
Formation Process
Hydrothermal; forms in geode cavities and veins from silica-rich solutions often in volcanic basalt
About This Crystal
Purple to violet transparent to translucent crystal; vitreous luster with conchoidal fracture patterns visible on surfaces
Physical Characteristics
Purple color; white streak; no cleavage; conchoidal fracture; specific gravity 2.65; can show weak fluorescence
Optical Properties
Refractive Index 1.544-1.553; uniaxial positive; weak pleochroism in shades of purple
Hardness & Durability
Origin Region
Notable sources include Brazil (Rio Grande do Sul), Uruguay (Artigas), Madagascar, Zambia, and Russia
Hardness & Durability
7 on Mohs scale; good toughness; stable but sensitive to extreme heat and prolonged UV exposure
Care & Maintenance
Clean with warm soapy water; avoid ultrasonic cleaners if fractured; store away from direct sunlight to prevent fading
Rarity & Value
Common globally; value determined by color depth (Siberian purple), clarity, and size; heat treatment is common to produce citrine
Special Characteristics
Can display color zoning and phantom growth patterns; piezoelectric properties typical of quartz
Lore & History
Historically believed by Ancient Greeks to prevent intoxication; associated with royalty and the Crown Chakra in traditional lore