Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; Hexagonal crystal system commonly found as prismatic crystals with pyrimidal terminations or as a druzy crust
Mineral Group
Silicates; Tectosilicate subgroup (Quartz group)
Chemical Formula
SiO2 (Silicon Dioxide) with traces of Iron (Fe4+) and natural irradiation
Formation Process
Hydrothermal formation; silica-rich fluids deposit in volcanic cavities (vugs/geodes) at low to medium temperatures (50-250°C) with ionizing radiation source for color.
About This Crystal
This specimen is a druzy amethyst cluster consisting of small, interlocking purple crystals on a gray-green matrix. It exhibits a vitreous luster, translucent transparency, and a classic lavender-to-violet color.
Physical Characteristics
Color: Pale violet to deep purple; Streak: White; Cleavage: None (poor); Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually inert or faint bluish-white under UV.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Optical Character: Uniaxial (+); Pleochroism: Weak to moderate in shades of purple.
Hardness & Durability
Origin Region
Notable sources include Rio Grande do Sul (Brazil), Artigas (Uruguay), Madagascar, Zambia, and Ontario (Canada); typically found in volcanic basalt geodes.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good (durable for most uses); Stability: Sensitive to high heat and prolonged direct sunlight which may cause fading.
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic cleaners and steam cleaning. Store away from direct sunlight and separate from harder gemstones like diamonds.
Rarity & Value
Common; value is determined by color intensity (deep Siberian purple is highest), clarity, and size. Most low-grade material is heat-treated to produce citrine.
Special Characteristics
Color zoning is common; many specimens show 'phantom' growth layers. The purple color is a result of iron impurities localized in the crystal lattice.
Lore & History
Ancient Greeks believed it prevented intoxication (the name comes from 'amethystos', meaning not drunk). Historically used by royalty and the clergy; it represents the Crown Chakra in modern healing lore.