Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically occurs as six-sided prismatic crystals terminating with rhombohedral faces. Can also be found as druzy or in massive form within geodes.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 (Silicon Dioxide) with trace amounts of Iron (Fe3+)
Formation Process
Hydrothermal / Volcanic; forms at low temperatures in igneous rocks and hydrothermal veins where silica-rich fluids deposit in cavities (amygdules) over long periods.
About This Crystal
Transparent to translucent purple macrocrystalline quartz. Luster is vitreous (glass-like). The specimen shown displays a deep violet color with typical conchoidal fracture patterns and some visible internal veining or color zoning.
Physical Characteristics
Color: Pale lilac to deep purple; Streak: White; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Generally inert, but some may show weak bluish or greenish glow under UV light.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Optical character: Uniaxial (+); Pleochroism: Weak to moderate in shades of purple and reddish-purple.
Hardness & Durability
Origin Region
Notable sources include Brazil (Rio Grande do Sul), Uruguay (Artigas), Madagascar, Zambia, and Russia (Ural Mountains). Often found in volcanic cavities or geode structures.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good (no cleavage); Stable for daily wear in jewelry but brittle enough to chip if struck against hard surfaces.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid ultrasonic cleaners if there are many inclusions. Keep away from prolonged direct sunlight as intense UV can cause the purple color to fade over time.
Rarity & Value
Very Common; value is determined by color saturation ('Deep Siberian' violet being most prized), clarity, and size. Common treatments include heat treatment (to turn it into citrine or green prasiolite).
Special Characteristics
Color zoning is extremely common, where the purple color is concentrated at the tips of the crystals. It may contain needle-like inclusions of goethite or cacoxenite.
Lore & History
Historically used in Ancient Greece to prevent intoxication (from the Greek 'amethystos', meaning 'not intoxicated'). It is traditionally associated with the Crown Chakra and believed to promote calm, clarity, and protection in spiritual practices.