Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal, with a macrocrystalline habit typically found as prismatic crystals terminating in rhombohedrons, though this specific specimen is a tumbled and polished pebble.
Mineral Group
Silicates, specifically Tectosilicates
Chemical Formula
SiO2
Formation Process
Hydrothermal and magmatic processes, forming as silica-rich solutions deposit quartz in gas cavities within volcanic rocks at low to moderate temperatures, with color imparted by trace iron irradiation.
About This Crystal
A tumbled, polished, asymmetrical pebble exhibiting translucent to semi-transparent properties. The specimen displays characteristic purple color zoning blending into milky white quartz patches, with visible internal fractures and surface weathering lines.
Physical Characteristics
Body color ranges from pale lilac to deep purple; streak is white; no true cleavage; fracture is conchoidal; specific gravity is approximately 2.65; brittle tenacity; exhibits piezoelectric properties.
Optical Properties
Uniaxial positive optical character with a refractive index of 1.544 to 1.553, showing weak dichroism in reddish-purple and bluish-purple shades.
Hardness & Durability
Origin Region
Notable sources include Brazil, Uruguay, Madagascar, Zambia, and the United States. Typically forms in volcanic rock cavities (geodes) or hydrothermal veins.
Hardness & Durability
Mohs hardness of 7, making it durable for general jewelry use with good wearability, though care must be taken against sharp impacts due to lack of cleavage and brittle fracture.
Care & Maintenance
Clean with warm soapy water using a soft brush; avoid harsh chemicals, ultrasonic cleaners, and prolonged exposure to direct sunlight, which can cause the purple coloration to fade.
Rarity & Value
Common; value depends on color saturation, transparency, and size, ranging from inexpensive tumbled stones to valuable deep-purple faceted gems, with heat treatment to yellow citrine being common.
Special Characteristics
Displays natural color zoning between purple amethyst and white quartz, and exhibits piezoelectricity under mechanical stress.
Lore & History
Historically worn by ancient Greeks and Romans to prevent intoxication, amethyst derives its name from the Greek word amethystos meaning not drunken. In modern crystal healing, it is traditionally associated with the third eye and crown chakras to promote inner peace, clarity, and spiritual growth.