Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal; typically prismatic with hexagonal cross-sections, often terminating in a rhombohedral point.
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2 (Silicon Dioxide) with trace amounts of Iron (Fe3+) and irradiation centers
Formation Process
Hydrothermal formation where silica-rich fluids crystallize in cavities (geodes) or veins within igneous or metamorphic rock at low to moderate temperatures.
About This Crystal
A violet to purple variety of quartz. This specimen shows a transition from translucent white/colorless quartz at the base to a saturated purple tip with a vitreous luster and uneven surfaces.
Physical Characteristics
Color: light to deep purple; Streak: white; Cleavage: none; Fracture: conchoidal to uneven; Specific Gravity: 2.65; Fluorescence: typically inert but may show weak greenish or reddish hues under UV.
Optical Properties
Uniaxial positive; Refractive Index: 1.544–1.553; Birefringence: 0.009; Weak pleochroism in purple/reddish-purple tones.
Hardness & Durability
Origin Region
Prominent sources include Brazil, Uruguay, Madagascar, and Zambia; typically found in volcanic geodes or hydrothermal veins.
Hardness & Durability
7 on the Mohs scale; Good toughness (no cleavage); stable for daily jewelry wear but susceptible to scratching by harder materials like Topaz or Diamond.
Care & Maintenance
Clean with warm soapy water; avoid ultrasonic or steam cleaners as they may trigger fractures in included stones; keep away from prolonged direct sunlight to prevent color fading.
Rarity & Value
Common; value depends on color saturation (deep 'Siberian' purple is most valuable), clarity, and size. Heat treatment is common to turn lower quality amethyst into citrine.
Special Characteristics
Color zoning is frequently visible; may contain phantom crystal inclusions or negative crystals; exhibits piezoelectricity.
Lore & History
Historically used by ancient Greeks to prevent intoxication ('amethystos' meaning 'not drunk'). Symbolizes royalty, peace, and spiritual protection; traditionally associated with the Third Eye and Crown chakras.