Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically found as hexagonal-shaped prisms with pyramidal terminations
Mineral Group
Silicates (Subgroup: Tectosilicates)
Chemical Formula
SiO2 (Silicon Dioxide with traces of Fe3+ iron impurities)
Formation Process
Hydrothermal formation within volcanic cavities (geodes) or pegmatites from silica-rich fluids at low-to-moderate temperatures
About This Crystal
Transparent to translucent purple variety of quartz. Displays a vitreous (glassy) luster with color ranging from pale lavender to deep royal purple. This faceted specimen shows characteristic triangular facet reflections and bright saturation.
Physical Characteristics
Color: Violet, purple, reddish-purple; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually inert but can show weak greenish-blue under UV
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009; Pleochroism: Weak to moderate in reddish-purple and bluish-purple tones; Optical character: Uniaxial positive
Hardness & Durability
Origin Region
Notable sources include Brazil (Rio Grande do Sul), Uruguay (Artigas), Madagascar, Zambia, and Russia (Urals)
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; Stability: Stable to light but may fade with prolonged exposure to high heat or intense UV
Care & Maintenance
Clean with warm soapy water and a soft brush; safe for ultrasonic cleaners unless it contains liquid inclusions. Store away from direct sunlight and harder gems like diamonds.
Rarity & Value
Common to Uncommon; Value depends on depth of color ('Siberian' dark purple is most prized). Often heat-treated to produce citrine or lightened to pale purple.
Special Characteristics
Color zoning is common (alternating saturated and clear bands); may contain internal inclusions like goethite needles or fluid-filled negative crystals.
Lore & History
Historically used by Ancient Greeks to prevent intoxication (name comes from 'amethystos' meaning 'not drunk'). Symbolizes royalty, peace, and spiritual protection; traditionally associated with the Crown Chakra.