Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal crystal system; typically occurs in hexagonal prismatic habits often terminated by rhombohedra; commonly found in druzy or geode formations.
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2 (Silicon Dioxide) with trace amounts of iron (Fe3+) and irradiation centers
Formation Process
Hydrothermal formation from silica-rich fluids at low to moderate temperatures (50-250°C) within cavities of igneous rocks such as basalt or in sedimentary geodes.
About This Crystal
A violet to purple variety of quartz. This specific specimen appears to be a light-colored, translucent to transparent fragment with a vitreous (glassy) luster and conchoidal fracture patterns.
Physical Characteristics
Color: Pale lavender to deep purple; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Generally inert, but may show weak blue/green under UV.
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009; Pleochroism: Weak to moderate in shades of purple and reddish-purple; Uniaxial (+).
Hardness & Durability
Origin Region
Major sources include Brazil (Rio Grande do Sul), Uruguay (Artigas), Madagascar, Zambia, and Russia (Ural Mountains). It typically forms in volcanic cavities or hydrothermal veins.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good (no cleavage); Stability: Generally stable but can fade with prolonged exposure to high heat or intense sunlight.
Care & Maintenance
Clean with warm soapy water and a soft brush; ultrasonic cleaners are usually safe unless there are liquid inclusions; avoid steam cleaning and prolonged exposure to direct sunlight to prevent fading.
Rarity & Value
Common; Value is determined by color saturation (deep purple with reddish flashes is most prized), clarity, and size. Most commercial amethyst is heat-treated to improve color or turn it into citrine.
Special Characteristics
Color zoning is very common in amethyst; it may occasionally show phantom inclusions or features like liquid-filled 'fingerprint' inclusions.
Lore & History
Historically used in ancient Greece to prevent intoxication ('amethystos' means 'not drunk'). It has been used in royal jewelry for centuries and is traditionally associated with the Crown Chakra, representing calm, clarity, and protection.