Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal, typically forming as prismatic crystals ending in a pyramid, but presented here as a polished tumbled stone
Mineral Group
Silicates (Tectosilicates)
Chemical Formula
SiO2
Formation Process
Hydrothermal and magmatic processes, typically forming within cavities and gas bubbles (vugs and geodes) in basaltic volcanic rocks at low to moderate temperatures
About This Crystal
A polished, translucent to transparent purple quartz gemstone showing internal fractures, veining, and striking rainbow iridescence from light interference within internal cleavage planes
Physical Characteristics
Purple body color ranging from light lilac to deep violet; white streak; conchoidal fracture; lacking distinct cleavage; specific gravity of approximately 2.65; brittle tenacity; exhibits piezoelectricity
Optical Properties
Uniaxial positive optical sign with a refractive index of 1.544 to 1.553, showing weak dichroism with reddish-purple and bluish-purple hues, and displaying optical interference colors (rainbow flashes) along internal fractures
Hardness & Durability
Origin Region
Global distribution with major deposits in Brazil, Uruguay, Madagascar, Zambia, and the United States (such as Arizona)
Hardness & Durability
Mohs hardness of 7, making it durable enough for everyday jewelry use though susceptible to scratching by harder minerals like topaz and corundum
Care & Maintenance
Clean safely using warm soapy water; avoid ultrasonic or steam cleaners if heavily fractured; store away from prolonged direct sunlight to prevent color fading
Rarity & Value
Common to moderately rare depending on saturation and clarity; value increases with deep purple color saturation and lack of visible inclusions; typically affordable unless of exceptional gem grade
Special Characteristics
Displays internal rainbow iridescence (fire/rainbow inclusions) due to light diffraction across micro-fractures inside the crystalline matrix
Lore & History
Historically worn by ancient Greeks and Romans to prevent intoxication and maintain a clear mind; culturally associated with royalty, spiritual clarity, and calmness, frequently linked to the third eye and crown chakras in modern crystal lore