Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal; typically prismatic with pyramidal terminations, though shown here as faceted and heart-shaped beads.
Mineral Group
Silicates; Tectosilicate subgroup
Chemical Formula
SiO2 (Silicon Dioxide) colored by iron (Fe3+) impurities and irradiation
Formation Process
Hydrothermal formation where silica-rich fluids deposit layers inside gas cavities (amygdules) in volcanic rock or in metamorphic veins.
About This Crystal
Transparent to translucent purple quartz. Luster is vitreous (glass-like). The image shows a mix of lighter lavender faceted rondelles and darker royal purple heart-shaped beads.
Physical Characteristics
Color: Pale lilac to deep purple; Streak: White; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Generally inert, occasionally weak blue/green.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Pleochroism: Weak to moderate in reddish-purple and bluish-purple tones; Uniaxial positive.
Hardness & Durability
Origin Region
Brazil (Rio Grande do Sul), Uruguay (Artigas), Zambia, and Madagascar. Forms in volcanic geode cavities and hydrothermal veins.
Hardness & Durability
Mohs Hardness: 7; Good durability for jewelry; brittle tenacity; no cleavage.
Care & Maintenance
Avoid prolonged direct sunlight (can fade), high heat, or harsh household chemicals. Clean with warm soapy water and a soft brush.
Rarity & Value
Highly abundant and common. Value is determined by color intensity (deep 'Siberian' purple is prized), clarity, and cut. Usually affordable.
Special Characteristics
Color zoning is common (alternating saturated and clear bands). It is the most popular variety of the quartz family.
Lore & History
Historically used by ancient Greeks to prevent intoxication ('amethystos' means 'not drunk'). Associated with the Crown Chakra and thought to promote calm and clarity.