Clear Quartz (Rock Crystal)
Silicon Dioxide var. Rock Crystal · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; hexagonal prism terminated by two rhombohedra
Mineral Group
Silicates (Tectosilicates)
Chemical Formula
SiO2
Formation Process
Primarily Hydrothermal: crystallization from silica-rich aqueous solutions in rock cavities at low to moderate temperatures
About This Crystal
Colorless, transparent to translucent crystalline aggregate with vitreous luster; exhibits conchoidal fracture surfaces that create internal rainbow 'fire' reflections (iris effect) as seen in the specimen
Physical Characteristics
Color: Colorless; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually none; Tenacity: Brittle
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009 (Uniaxial positive); Dispersion: 0.013; Optical phenomena: Iris effect/Iridescence due to internal fractures
Hardness & Durability
Origin Region
Worldwide; notably Brazil, Arkansas (USA), and Madagascar in hydrothermal veins and pegmatites
Hardness & Durability
Mohs Hardness: 7; Toughness: Good (no cleavage); Stability: High (resistant to most acids and heat)
Care & Maintenance
Safe with warm soapy water and ultrasonic cleaners; store away from harder stones like Sapphire or Diamond to prevent scratching
Rarity & Value
Common; Value based on clarity and crystal size; highly affordable; typically untreated although sometimes irradiated to produce Smokey Quartz
Special Characteristics
Piezoelectric and pyroelectric properties; this specimen shows internal iridescence (rainbows) caused by light interference in thin film air gaps within fractures
Lore & History
Historically known as 'frozen ice' by ancient Greeks (Krystallos). Culturally used as a 'Master Healer' stone in traditional crystal lore, associated with the Crown Chakra and amplification of energy.