Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; habitually occurs as hexagonal prisms terminated by rhombohedra, often found in geodes, clusters, or massive form
Mineral Group
Silicates; Tectosilicate subgroup (Quartz group)
Chemical Formula
SiO2 (Silicon Dioxide) with traces of Iron (Fe4+) and natural irradiation
Formation Process
Hydrothermal; forms from silica-rich fluids in cavities (vugs) or geodes within igneous rocks as they cool, or in metamorphic environments
About This Crystal
A violet to purple variety of quartz. This specific specimen is an unpolished, rough fragment showing a deep purple hue with white milky quartz veining. It is translucent to transparent with a vitreous luster and conchoidal fracture surfaces
Physical Characteristics
Color: light to deep purple; Streak: white; Cleavage: none; Fracture: conchoidal; Specific Gravity: 2.65; Fluorescence: typically inert but can show weak greenish/blue under UV
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009; Optical character: Uniaxial positive; Weak pleochroism (purple/reddish-purple)
Hardness & Durability
Origin Region
Notable sources include Brazil (Rio Grande do Sul), Uruguay (Artigas), Madagascar, Zambia, and Russia; typically found in volcanic geodes or hydrothermal veins
Hardness & Durability
Mohs Hardness: 7; Toughness: Good (no cleavage); Stable for jewelry but sensitive to high heat and prolonged direct sunlight
Care & Maintenance
Clean with warm soapy water; avoid ultrasonic cleaners or steam if inclusions are present. Store away from direct sunlight to prevent color fading over time
Rarity & Value
Common; value is determined by color intensity (deep 'Siberian' purple is most prized), clarity, and size. Frequent treatments include heat to lighten dark stones or produce Citrine
Special Characteristics
Color zoning (color concentrated at crystal tips), phantom growth layers, and liquid or 'tiger-stripe' inclusions common in natural specimens
Lore & History
Historically used by Ancient Greeks to prevent intoxication (ame-thystos meaning 'not drunk'); traditionally associated with the Crown Chakra, peace, and spiritual protection