Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal crystal system; habit is typically hexagonal prisms with pyramidal terminations, commonly found as druzy or in geodes.
Mineral Group
Silicates (Subgroup: Tectosilicate)
Chemical Formula
SiO2 with trace amounts of Iron (Fe3+)
Formation Process
Hydrothermal formation; colors are produced by gamma irradiation of iron impurities in quartz at temperatures below 420 degrees Celsius.
About This Crystal
A violet to purple variety of quartz. This specimen is a heart-shaped druzy cluster of small, translucent to transparent crystals with vitreous luster and visible pyramid terminations.
Physical Characteristics
Color: Pale lavender to deep purple; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Generally inert but can show weak greenish/blue under UV.
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009; Optically Uniaxial (+) with weak pleochroism in shades of purple and reddish-purple.
Hardness & Durability
Origin Region
Notable sources include Brazil (Rio Grande do Sul), Uruguay (Artigas), Madagascar, and Russia. Found often in volcanic basalt cavities.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; Stability: Stable to light but may fade with prolonged exposure to high heat or intense direct sunlight.
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic cleaners if the specimen has fractures; store away from direct sunlight to prevent color fading.
Rarity & Value
Common; Value is driven by color saturation (deep purple with red flashes is premium), clarity, and size. Frequently natural, but can be heat-treated to create Citrine.
Special Characteristics
Often displays color zoning; may contain internal inclusions like goethite needles or fluid-filled cavities (enhydros).
Lore & History
Historically used by Ancient Greeks to prevent intoxication ('amethystos' meaning not drunk). Symbolizes peace and clarity; traditionally associated with the Crown Chakra.