Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal crystal system; the specimen shown is a tumbled or polished 'massive' habit, but naturally forms as hexagonal prisms with pyramidal terminations.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 with trace amounts of Iron (Fe3+)
Formation Process
Hydrothermal formation within cavities of volcanic rock (geodes) or in pegmatites through the crystallization of silica-rich fluids at low to moderate temperatures.
About This Crystal
A translucent to transparent purple variety of quartz. This specific specimen is a small tumbled stone, roughly 1.3cm in size, displaying a vitreous luster and characteristic purple color zoning with light white or clear inclusions.
Physical Characteristics
Color: light to dark purple; Streak: white; Cleavage: none; Fracture: conchoidal; Specific Gravity: 2.65; Fluorescence: typically inert but may show weak greenish or bluish tones under UV.
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: +0.009; Pleochroism: weak to moderate purple and reddish-purple; Doubly refractive (uniaxial).
Hardness & Durability
Origin Region
Major sources include Brazil, Uruguay, Madagascar, and Zambia; typically found in volcanic geodes or hydrothermal veins.
Hardness & Durability
Mohs hardness: 7.0; Toughness: Good, though can be brittle; excellent for all types of jewelry.
Care & Maintenance
Clean with warm soapy water; safe for ultrasonic unless heavily included; should be kept away from prolonged direct sunlight to prevent color fading.
Rarity & Value
Common and abundant worldwide. Value is determined by color intensity (deep Siberian purple is most prized) and clarity. Heat treatment is common to produce Citrine or lighten dark stones.
Special Characteristics
Displays color zoning (uneven color distribution) and may contain fluid inclusions or 'tiger stripe' fracture patterns inside the crystal structure.
Lore & History
Historically used in Ancient Greece to prevent intoxication (Greek 'amethystos' means 'not drunk'). Symbolizes wisdom and peace in various cultures; traditionally associated with the Crown Chakra.