Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal; typical habit is hexagonal prism terminated by two sets of rhombohedrons; also occurs in geodes and druzy form.
Mineral Group
Silicates; Tectosilicate subgroup
Chemical Formula
SiO2 (Silicon Dioxide) with trace amounts of iron (Fe3+) and natural irradiation
Formation Process
Hydrothermal; forms from silica-rich solutions in cavities or cracks within igneous or metamorphic rocks at relatively low temperatures.
About This Crystal
A deep purple, translucent to transparent crystal. The specimen shown is a polished 'tower' or point, exhibiting a vitreous (glass-like) luster and characteristic color zoning ranging from pale lilac to deep indigo.
Physical Characteristics
Color: Purple to violet; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually inert but can show weak green or blue under UV.
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, Uruguay, Zambia, Madagascar, and Russia; typically found in volcanic cavities (geodes) or hydrothermal veins.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; Highly durable for all jewelry types, though it lacks cleavage which prevents easy splitting.
Care & Maintenance
Clean with warm soapy water; avoid ultrasonic or steam cleaners. Store away from direct sunlight as prolonged exposure can cause the purple color to fade.
Rarity & Value
Common; value is determined by color depth (Siberian purple being most prized) and clarity. Generally affordable, widely treated via heat to produce Citrine.
Special Characteristics
Color zoning is very common; can contain 'tiger stripe' inclusions or liquid-filled cavities. It is the purple variety of the quartz family.
Lore & History
Historically used by ancient Greeks to prevent intoxication (named from 'amethystos', meaning not drunk). Traditionally associated with the Crown Chakra and believed to promote calm and clarity.