Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal, with a microcrystalline to macrocrystalline habit; typically forms as prismatic hexagonal crystals terminating in pyramids, but found here as a tumbled, rounded pebble.
Mineral Group
Silicates (Subgroup: Tectosilicate)
Chemical Formula
SiO2
Formation Process
Hydrothermal and magmatic processes, precipitating from silica-rich aqueous solutions within cavities of volcanic rocks at low to moderate temperatures and pressures.
About This Crystal
A tumbled, polished specimen showing deep purple to violet coloration with white bands or quartz inclusions. It is translucent to semi-translucent with a vitreous to waxy luster due to tumbling.
Physical Characteristics
Purple body color with a white streak, lack of distinct cleavage (conchoidal fracture), specific gravity of approximately 2.65, brittle tenacity, and generally inert to UV light.
Optical Properties
Uniaxial positive with a refractive index of 1.544-1.553, low birefringence of 0.009, and faint dichroism showing reddish-purple and bluish-purple shades.
Hardness & Durability
Origin Region
Brazil, Uruguay, Madagascar, Zambia, and the United States; commonly forms in volcanic rock cavities or hydrothermal veins.
Hardness & Durability
Mohs hardness of 7, making it durable for daily jewelry wear with good resistance to scratching, though lacking cleavage, it can shatter under severe impact.
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid harsh chemicals, ultrasonic cleaners, and prolonged exposure to direct sunlight to prevent color fading.
Rarity & Value
Common; value depends on color saturation, clarity, and size. Tumbled stones are inexpensive and widely accessible.
Special Characteristics
Displays characteristic chevron or banded color zoning mixing deep purple and white milky quartz.
Lore & History
Historically used by ancient Greeks and Egyptians as a protective amulet against intoxication and negative energy. Associated in modern crystal healing with the third eye and crown chakras to promote inner peace and clarity.