Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone and Mineral Specimen
Crystal System
Trigonal, prismatic crystal habit terminating in six-sided pyramids, often forming druzy clusters or geodes.
Mineral Group
Silicates, specifically Tectosilicates
Chemical Formula
SiO2
Formation Process
Hydrothermal and magmatic processes, typically crystallizing from silica-rich solutions in gas cavities within basaltic lavas at low to moderate temperatures.
About This Crystal
Displays clusters of purple quartz crystals varying from pale lilac to deep violet. Crystals show typical hexagonal prism faces with pyramidal terminations, growing outwards from a chalcedony and matrix base. Transparency ranges from transparent to translucent with a vitreous luster.
Physical Characteristics
Color is purple due to irradiation and trace iron impurities; white streak; no true cleavage, exhibits conchoidal fracture; specific gravity of approximately 2.65; brittle tenacity; exhibits piezoelectricity.
Optical Properties
Uniaxial positive with a refractive index of 1.544-1.553, showing weak birefringence and faint dichroism in shades of purplish-red and bluish-purple.
Hardness & Durability
Origin Region
Notable sources include Brazil, Uruguay, Madagascar, Zambia, and the United States (Thunder Bay). Forms in volcanic gas cavities, hydrothermal veins, and pegmatites.
Hardness & Durability
Mohs hardness of 7, making it durable for daily wear in jewelry, though caution is required with sharp impacts due to lack of cleavage causing brittle fracture.
Care & Maintenance
Clean with warm soapy water using a soft brush. Avoid harsh chemicals, ultrasonic cleaners, and prolonged direct sunlight which can cause the purple color to fade.
Rarity & Value
Common to moderately rare depending on color saturation and clarity. Deep Siberian or Uruguayan grades are more valuable. Heat treatment is sometimes used to convert low-grade material to citrine or green prasiolite.
Special Characteristics
Color zoning is common, with color concentrated at the tips of the crystals. Exhibits piezoelectric and pyroelectric properties.
Lore & History
Historically used as a talisman by ancient Greeks and Romans to prevent drunkenness. Associated with the third eye and crown chakras, traditionally believed to promote calmness, spiritual growth, and clarity of mind.