Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal; typically occurs as hexagonal prisms terminated by rhombohedral faces. Common in geodes and druzes.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 (Silicon Dioxide with Fe3+ Iron impurities)
Formation Process
Hydrothermal; forms from silica-rich solutions in cavities (amygdules) within volcanic rocks or in mineral veins at low to moderate temperatures.
About This Crystal
Transparent to translucent purple variety of quartz. This specimen shows a pale lilac color with a vitreous to glassy luster and conchoidal fracturing. Internal veining and inclusions are visible.
Physical Characteristics
Color: Pale purple to deep violet. Streak: White. Cleavage: None. Fracture: Conchoidal. Specific Gravity: 2.65. Fluorescence: Usually inert but can show weak phosphorescence.
Optical Properties
Uniaxial positive. Refractive Index: 1.544–1.553. Birefringence: 0.009. Pleochroism: Weak to moderate in purple tones.
Hardness & Durability
Origin Region
Brazil (notably Rio Grande do Sul), Uruguay, Zambia, and Madagascar. Found in volcanic cavities and hydrothermal veins.
Hardness & Durability
Mohs Hardness: 7. Toughness: Good. Stability: Stable but can fade upon prolonged exposure to intense sunlight or heat.
Care & Maintenance
Clean with warm soapy water. Avoid ultrasonic cleaners if there are many inclusions. Keep away from high heat and prolonged direct sunlight to prevent color loss.
Rarity & Value
Common. Value is determined by color saturation (deeper purple is more valuable), clarity, and size. Frequently heat-treated to produce Citrine.
Special Characteristics
Color zoning is common. May contain 'tiger stripe' inclusions or liquid-gas feathers. Some specimens exhibit weak dichroism.
Lore & History
Ancient Greeks believed it prevented intoxication (amethystos literally means 'not drunken'). Associated with royalty and the Crown Chakra in traditional crystal healing lore.