Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal, typically forming prismatic crystals terminating in rhombohedrons, often found as massive, druzy, or within geodes
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2
Formation Process
Hydrothermal and magmatic processes, precipitating from silica-rich solutions at low to moderate temperatures with iron impurities irradiated by natural gamma rays
About This Crystal
A polished, translucent to transparent purple quartz specimen displaying characteristic geometric color zoning, angular banding, and internal fractures with minor inclusions
Physical Characteristics
Light to medium purple body color, white streak, conchoidal fracture, lack of cleavage, specific gravity of approximately 2.65, brittle tenacity, and generally inert to weak fluorescence under UV light
Optical Properties
Uniaxial positive optical sign, refractive index of 1.544 to 1.553, birefringence of 0.009, doubly refractive, and weak dichroism showing reddish-purple and bluish-purple shades
Hardness & Durability
Origin Region
Brazil, Uruguay, Madagascar, Zambia, and the USA; forms in volcanic cavities, hydrothermal veins, and pegmatites
Hardness & Durability
Mohs hardness of 7, fair toughness due to lack of cleavage, good chemical stability, and suitable for most types of jewelry with normal wear
Care & Maintenance
Clean with warm soapy water using a soft brush, avoid harsh chemicals and ultrasonic cleaners if heavily fractured, and store away from prolonged direct sunlight to prevent color fading
Rarity & Value
Common to uncommon depending on color saturation and clarity; valued based on deep purple color, transparency, and lack of visible inclusions; heat treatment is occasionally used to convert lower-grade material to yellow citrine
Special Characteristics
Features distinct chevron or angular color zoning bands and phantom-like internal growth lines visible under backlighting
Lore & History
Historically worn in ancient times to prevent intoxication and promote clear-headedness; associated in modern crystal healing traditions with the third eye and crown chakras for spiritual growth and calm