Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; Hexagonal dipyramidal. Habits include prismatic crystals, massive forms, druses, and geodes.
Mineral Group
Silicates; Tectosilicate (Framework Silicate) subgroup; Quartz group.
Chemical Formula
SiO2 (Silicon Dioxide) with trace amounts of iron (Fe3+) and irradiation-induced color centers
Formation Process
Hydrothermal formation where silica-rich fluids deposit layers inside rock cavities (geodes) or veins. Color is the result of iron impurities and natural radiation during cooling.
About This Crystal
Transparent to translucent violet quartz. The specimens shown include a polished tumbled stone (left) and a rough crystal point (right). Luster is vitreous (glass-like). Appearance ranges from pale lavender to deep royal purple with possible color zoning.
Physical Characteristics
Color: Purple, Violet; Streak: White; Cleavage: None; Fracture: Conchoidal (shell-like); Specific Gravity: 2.65; Fluorescence: Generally inert, but some may show weak bluish or greenish tones under UV.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Optical Character: Uniaxial (+); Pleochroism: Weak to moderate in purple and reddish-purple tones.
Hardness & Durability
Origin Region
Brazil (Rio Grande do Sul), Uruguay (Artigas), Madagascar, Zambia, and Russia. Found in basaltic geodes and hydrothermal veins.
Hardness & Durability
Mohs Hardness: 7. Toughness is good (no cleavage), making it highly durable for all jewelry types. Stable under normal conditions.
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 it may cause the color to fade over time.
Rarity & Value
Common; Value is determined by color saturation (deep purple with red/blue flashes is highest), clarity, and size. Most affordable of the quartz varieties.
Special Characteristics
Color zoning (stripes of darker/lighter purple) and 'tiger-stripe' inclusions. Occasionally exhibits phantoms (visible growth lines of earlier crystal stages).
Lore & History
Historically used by ancient Greeks and Romans to prevent intoxication (Greek 'amethystos' means 'not drunk'). Associated with the Crown Chakra, sobriety, and tranquility in traditional lore.