Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically occurs as hexagonal prisms terminated by two sets of rhombohedrons, or as druzy aggregates within geodes.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 (Silicon Dioxide) with traces of Iron (Fe4+) and natural irradiation
Formation Process
Hydrothermal; forms in cavities (geodes) of volcanic rocks or hydrothermal veins when silica-rich fluids cool and crystallize.
About This Crystal
Transparent to translucent violet quartz. This specific fragment shows a pale lavender to lilac color, vitreous luster, and a conchoidal fracture pattern. It appears as a broken crystal shard without distinct terminal faces.
Physical Characteristics
Color: Violet to purple; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually inert but can show weak green/blue under UV.
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009; Uniaxial (+); Pleochroism: Weak to moderate in shades of purple and reddish-purple.
Hardness & Durability
Origin Region
Major sources include Brazil (Rio Grande do Sul), Uruguay (Artigas), Madagascar, Zambia, and Russia (Ural Mountains).
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; stable for jewelry but sensitive to high heat and prolonged direct sunlight.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid ultrasonic cleaners if inclusions are present. Store away from direct sunlight to prevent color fading.
Rarity & Value
Common; Value determined by color saturation (deep 'Siberian' purple is highest), clarity, and size. Heat treatment to turn it into citrine is common.
Special Characteristics
Color zoning is common (alternating light and dark bands); may contain 'tiger stripe' inclusions or goethite needles.
Lore & History
Historically used by ancient Greeks to prevent intoxication (name derives from 'amethystos' meaning 'not drunk'). Associated with the Crown Chakra and believed to promote calm and clarity.