Amethyst
Quartz var. Amethyst (IMA-approved: Quartz) · Semi-Precious Gemstone
Crystal System
Trigonal; typically occurs in hexagonal prism habits capped by rhombohedral terminal faces. This specimen is a tumbled/polished freeform shape.
Mineral Group
Silicates; Tectosilicate subgroup.
Chemical Formula
SiO2 (Silicon Dioxide) with color resulting from trace amounts of irradiation and iron (Fe3+) impurities.
Formation Process
Hydrothermal; formed from silica-rich solutions at relatively low temperatures (50–250°C) deposited within cavities of volcanic basalt or sedimentary rocks.
About This Crystal
Transparent to translucent purple quartz. This specimen exhibits light lavender to lilac coloration with internal milky clouds, fractures, and a vitreous luster. Surface shows modern polishing for lapidary use.
Physical Characteristics
Color: Lavender/Purple; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Tenacity: Brittle; Fluorescence: Generally inert, but may show weak blue/green under UV.
Optical Properties
Uniaxial positive; Refractive Index: 1.544–1.553; Birefringence: 0.009; Pleochroism: Weak to moderate purple to reddish-purple; shows internal iris effect (rainbow) due to light interference in internal fractures.
Hardness & Durability
Origin Region
Major sources include Brazil (Rio Grande do Sul), Uruguay (Artigas), Madagascar, Zambia, and Russia. Typically found in volcanic geodes and hydrothermal veins.
Hardness & Durability
Mohs hardness: 7.0; Good toughness for daily wear; stable under most conditions but sensitive to extreme heat and prolonged UV exposure.
Care & Maintenance
Clean with warm soapy water. Avoid ultrasonic or steam cleaners if significant internal fractures are present. Store away from direct sunlight to prevent color fading over time.
Rarity & Value
Common; Value is determined by color saturation ('deep Siberian' purple is highest), clarity, and size. Mass-market tumbled stones like this are low-cost, usually $1-$10 depending on size.
Special Characteristics
Displays internal 'rainbow' reflections (iridescence) caused by light interference along thin internal fracture planes or 'feathers'. Piezoelectric properties are present.
Lore & History
Historically worn by ancient Greeks to prevent intoxication (from 'amethystos,' meaning 'not drunk'). In crystal healing, it is traditionally associated with the Crown Chakra, sobriety, and calming the mind.