Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal, with a prismatic habit terminated by rhombohedra, often exhibiting horizontal striations on the prism faces.
Mineral Group
Silicates (Subgroup: Tectosilicate)
Chemical Formula
SiO2
Formation Process
Hydrothermal and magmatic processes, typically crystallizing from silica-rich solutions within gas cavities (vesicles) in basaltic volcanic rocks at low to moderate temperatures.
About This Crystal
A polished or naturally terminated single quartz crystal point displaying a deep purple to violet body color. It is translucent to semi-transparent with a vitreous luster, featuring distinct horizontal striations along the prism face and brownish matrix or iron oxide inclusions on the exterior surface.
Physical Characteristics
Color ranges from pale lilac to deep purple; streak is white; cleavage is absent (exhibits conchoidal fracture); specific gravity is approximately 2.65; tenacity is brittle; exhibits piezoelectric properties.
Optical Properties
Singly or doubly refractive (uniaxial positive) with a refractive index of 1.544 to 1.553, low birefringence of 0.009, and weak dichroism displaying reddish-purple and bluish-purple hues.
Hardness & Durability
Origin Region
Found globally with notable sources in Brazil, Uruguay, Madagascar, Zambia, and the United States (Thunder Bay, Ontario). Typically forms in volcanic rock cavities or hydrothermal veins.
Hardness & Durability
Mohs hardness of 7, making it durable and suitable for general jewelry use, though vulnerable to thermal shock and strong impacts due to its brittle tenacity and lack of cleavage.
Care & Maintenance
Clean safely with warm, soapy water and a soft brush. Avoid ultrasonic cleaners, steam cleaning, harsh chemicals, and prolonged exposure to direct sunlight, which can cause the purple color to fade.
Rarity & Value
Common to moderately rare depending on color saturation and clarity. Value is determined by deep purple saturation, transparency, and size. Common enhancements include heat treatment to produce yellow citrine or green prasiolite.
Special Characteristics
Often exhibits distinct color zoning parallel to the crystal faces, and natural irradiation-induced color centers involving trace iron impurities. May contain fluid or mineral inclusions.
Lore & History
Historically worn by ancient Greeks and Romans to prevent intoxication and maintain a clear mind. Widely used in modern crystal healing traditions for calming the mind, balancing the third eye and crown chakras, and promoting spiritual growth.