Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal, with a microcrystalline or massive tumbled habit in this polished specimen
Mineral Group
Silicates (Subgroup: Tectosilicates)
Chemical Formula
SiO2
Formation Process
Hydrothermal and magmatic processes, precipitating from silica-rich solutions in gas cavities within volcanic rocks at low to moderate temperatures
About This Crystal
A polished, rounded tumbled stone exhibiting a deep purple body color with translucent to semi-translucent clarity and a vitreous to waxy luster typical of a tumbled quartz variety
Physical Characteristics
Purple color ranging from pale lilac to deep violet, white streak, no cleavage, conchoidal fracture, specific gravity of approximately 2.65, brittle tenacity, and generally inert or weak yellowish fluorescence under UV light
Optical Properties
Uniaxial positive optical character with a refractive index of 1.544 to 1.553, low birefringence of 0.009, and faint weak pleochroism in reddish-violet and bluish-violet
Hardness & Durability
Origin Region
Brazil, Uruguay, Madagascar, and Zambia; typically found in volcanic gas cavities and hydrothermal veins
Hardness & Durability
Mohs hardness of 7, fair to good toughness, stable under normal conditions, making it well-suited for various types of jewelry wear
Care & Maintenance
Clean with warm soapy water using a soft brush, avoid harsh chemicals and prolonged exposure to direct sunlight which can cause the purple color to fade
Rarity & Value
Common to moderately rare depending on color saturation and clarity; valued based on deep saturation, lack of inclusions, and size, with widespread availability and occasional heat-treatment enhancement to produce yellow citrine or green prasiolite
Special Characteristics
Displays typical quartz piezoelectric properties and natural color zoning often visible as bands of lighter and darker purple
Lore & History
Historically worn in ancient times to prevent intoxication and promote clear-headedness; widely associated today with the third eye and crown chakras, tranquility, and spiritual growth in crystal lore