Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal; hexagonal prisms, commonly found as geodes or massive tumbled stones
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 (Silicon Dioxide) with trace amounts of Iron (Fe3+) and natural irradiation
Formation Process
Forms in igneous environments, typically within gas cavities (vesicles) of basaltic rocks or in hydrothermal veins through low-temperature mineral-rich water precipitation.
About This Crystal
This specimen is a deep purple, translucent to semi-opaque tumbled stone. It exhibits a vitreous (glass-like) luster with visible internal fractures and cloudy inclusions characteristic of natural quartz.
Physical Characteristics
Color: Violet to deep purple; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Generally inert to weak blue.
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009; Pleochroism: Weak to moderate purple to reddish-purple; Optical Character: Uniaxial positive.
Hardness & Durability
Origin Region
Notable sources include Brazil (Rio Grande do Sul), Uruguay (Artigas), Zambia, and Madagascar. Found in volcanic cavities and hydrothermal veins.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good (no cleavage); Stability: Generally stable but can fade if exposed to prolonged intense sunlight.
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic cleaners and harsh chemicals; store away from direct sunlight to prevent color fading.
Rarity & Value
Common; value is determined by color intensity (deep Siberian purple is highest), clarity, and size. Frequently natural, but can be heat-treated to produce Citrine.
Special Characteristics
Possesses piezoelectric properties; may show color-zoning or 'phantom' inclusions where earlier stages of crystal growth are visible.
Lore & History
Historically used by Ancient Greeks and Romans to prevent intoxication (from 'amethystos', meaning 'not intoxicated'). Often associated with the Crown Chakra and believed to promote calm and spiritual clarity.