Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal; typically occurs in hexagonal prismatic crystals or as massive, tumbled specimens like this teardrop shape
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 (Silicon Dioxide) with trace amounts of Fe3+ (Iron) and natural irradiation
Formation Process
Hydrothermal crystallization from silica-rich fluids in volcanic igneous rocks or metamorphic cavities
About This Crystal
A tumbled, teardrop-shaped specimen exhibiting a lavender to deep purple color with subtle white or smoky zoning. It has a vitreous (glassy) luster and is translucent to transparent.
Physical Characteristics
Color: Purple; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually inert/weakly bluish under UV
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009; Optically uniaxial (+); pleochroism is weak (purple to reddish-purple)
Hardness & Durability
Origin Region
Brazil, Uruguay, Madagascar, and Zambia; commonly formed in volcanic cavities (geodes)
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; High durability and excellent for daily jewelry wear
Care & Maintenance
Wash with warm soapy water; avoid prolonged exposure to direct sunlight as UV can fade the color; avoid sudden temperature changes
Rarity & Value
Common; value depends on color saturation (deeper purple is higher value) and clarity; often heat-treated to produce Citrine
Special Characteristics
Color zoning (different shades in the same stone), 'Tiger stripes' or 'Zebra' inclusions typical of quartz, and potential for phantom inclusions
Lore & History
Historically used in Ancient Greece to prevent intoxication; associated with the crown chakra and believed to promote calm, clarity, and protection.