Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically occurs in hexagonal prismatic habits with pyramidal terminations
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2 (Silicon Dioxide with traces of Iron Fe3+)
Formation Process
Hydrothermal; forms in cavities (geodes) of volcanic rocks (basalt) or in hydrothermal veins through crystallization from silica-rich fluids.
About This Crystal
This specimen is a druzy cluster of translucent to transparent purple crystals. It exhibits a deep violet hue with vitreous (glassy) luster and typical small pyramidal crystal faces.
Physical Characteristics
Color: Violet to deep purple; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually inert but can be weak blue.
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009 (Uniaxial positive); Pleochroism: Weak to moderate in shades of purple.
Hardness & Durability
Origin Region
Notable sources include Brazil (Rio Grande do Sul), Uruguay (Artigas), Madagascar, Russia, and Zambia. Often found in volcanic geodes.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; stable for jewelry, though sensitive to extreme thermal shock.
Care & Maintenance
Clean with warm soapy water. Avoid ultrasonic cleaners and steam. Store away from direct sunlight as prolonged exposure can cause the purple color to fade.
Rarity & Value
Common globally; value is determined by color intensity (deep 'Siberian' purple is most valuable), clarity, and size. Heat treatment can turn it into citrine.
Special Characteristics
Color zoning is common. This specific specimen shows a druzy habit and contains potential iron oxide inclusions giving it a dark, saturated appearance.
Lore & History
Ancient Greeks believed it prevented intoxication (amethystos means 'not drunk'). It has been used for centuries in royal jewelry and is traditionally associated with the crown chakra and spiritual clarity.