Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal; typically occurs as hexagonal prisms or in massive/tumbled forms; may exhibit Brazil-law twinning
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 (Silicon Dioxide) with trace amounts of Iron (Fe3+)
Formation Process
Hydrothermal; forms in cavities (geodes) of volcanic rocks through the precipitation of silica-rich fluids at low to moderate temperatures
About This Crystal
A violet to purple variety of quartz. This specific tumbled specimen exhibits color zoning with shades of deep purple and white/clear areas. It has a vitreous luster and is translucent to transparent in different sections.
Physical Characteristics
Color: light to dark purple; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Generally inert, occasionally weak bluish under UV
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009; Pleochroism: Weak to moderate in dichroic purple tones; Uniaxial positive
Hardness & Durability
Origin Region
Brazil, Uruguay, Zambia, Madagascar; commonly found in volcanic geodes and hydrothermal veins
Hardness & Durability
Mohs Hardness: 7; Toughness: Good (no cleavage); stable for everyday wear in jewelry but sensitive to high heat
Care & Maintenance
Clean with warm soapy water; avoid ultrasonic cleaners if the stone has fractures; store away from direct sunlight to prevent color fading
Rarity & Value
Common; value depends on color saturation, clarity, and size. Deep 'Siberian' purple is most valued; treatments like heat are used to create Citrine
Special Characteristics
Color zoning (tiger-stripe like patterns), possible inclusion of iron oxides or negative crystals; known for its distinct purple hue caused by radiation-induced centers in iron-bearing quartz
Lore & History
Historically associated with preventing intoxication; used by Ancient Greeks and Romans. Symbolizes peace and protection; traditionally linked to the Crown and Third Eye chakras