Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; hexagonal prism habit, though this specimen is tumbled/irregular
Mineral Group
Silicates; Tectosilicate subgroup (Quartz group)
Chemical Formula
SiO2 (Silicon Dioxide) with trace amounts of Iron (Fe3+) and irradiation centers
Formation Process
Hydrothermal crystallization from silica-rich fluids in volcanic cavities (vugs) or pegmatites at low to moderate temperatures.
About This Crystal
This is a small, tumbled or water-worn purple specimen. It exhibits a deep violet to pale lavender color zoning with translucent to transparent areas and a vitreous (glassy) luster. The specimen is approximately 1.5 cm in width based on the ruler.
Physical Characteristics
Color: Purple to violet; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually inert but can show weak green/blue under UV.
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009 (doubly refractive); Pleochroism: Weak to moderate purple/reddish-purple.
Hardness & Durability
Origin Region
Notable sources include Brazil, Uruguay, Madagascar, and Zambia. Commonly found in volcanic geodes or hydrothermal veins.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good (no cleavage); Stable for jewelry, though sensitive to high heat and prolonged direct sunlight.
Care & Maintenance
Clean with warm soapy water. Avoid ultrasonic cleaners if there are many inclusions. Keep away from prolonged direct sunlight to prevent fading. Avoid harsh chemicals.
Rarity & Value
Common, but high-grade deep purple pieces are more valuable. Treatments: Often heat-treated to produce citrine or prasiolite; some light stones are irradiated to deepen color.
Special Characteristics
Color zoning (uneven distribution of purple), possible smoky quartz inclusions, and characteristic conchoidal fracture visible in chipped areas.
Lore & History
Ancient Greeks believed it prevented intoxication (amethystos = 'not drunken'). It has been used in royal jewelry for centuries and is traditionally associated with the Crown Chakra and spiritual protection.