Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal; typically prismatic with pyramidal terminations, often found as geode linings or clusters.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 with trace amounts of Iron (Fe3+)
Formation Process
Hydrothermal; forms in silica-rich fluids within cavities of volcanic rocks (basalt) or metamorphic environments.
About This Crystal
A violet to purple variety of quartz. It features a vitreous luster, ranging from transparent to translucent with characteristic color zoning and liquid or 'tiger stripe' inclusions.
Physical Characteristics
Color: Light lavender to deep royal purple; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Generally inert, occasionally weak bluish.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Pleochroism: Weak to moderate purple/red-purple; Doubly refractive (uniaxial positive).
Hardness & Durability
Origin Region
Brazil, Uruguay, Madagascar, Zambia, and Russia. Often found in volcanic geodes or hydrothermal veins.
Hardness & Durability
Mohs Hardness: 7; Good toughness and high durability for all jewelry types; sensitive to high heat.
Care & Maintenance
Clean with warm soapy water. Avoid ultrasonic cleaners and steam. Keep away from prolonged direct sunlight to prevent color fading.
Rarity & Value
Common; Value is driven by deep 'Siberian' purple saturation with red/blue flashes. Larger, eye-clean specimens are most prized.
Special Characteristics
Exhibits color zoning and can contain 'color-box' phantom inclusions or rutile needles; turns yellow (citrine) or green (prasiolite) when heated.
Lore & History
Ancient Greeks believed it prevented intoxication (amethystos: 'not drunk'). Historically a stone of royalty and spiritual protection, associated with the Crown Chakra.