Clear Quartz (Rock Crystal)
Quartz (Silica) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically hexaganol prisms terminated by rhombohedral faces. Massive or crystalline habit.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2
Formation Process
Hydrothermal or Igneous; forms via crystallization from magma or precipitation from hot, silica-rich hydrothermal veins.
About This Crystal
Transparent, colorless stone with a vitreous luster. Features conchoidal fracture patterns and internal feather-like inclusions.
Physical Characteristics
Colorless, white streak, no cleavage, conchoidal fracture, 2.65 specific gravity, non-fluorescent (usually).
Optical Properties
Refractive Index: 1.544-1.553. Birefringence: 0.009. Uniaxial positive. Doubly refractive.
Hardness & Durability
Origin Region
Found globally; major deposits in Brazil, Arkansas (USA), Madagascar, and the Alps.
Hardness & Durability
Mohs hardness 7. Very durable and stable for daily jewelry wear.
Care & Maintenance
Safe to clean with warm soapy water or ultrasonic cleaners. Resistance to most chemicals except hydrofluoric acid.
Rarity & Value
Common. Value is determined by clarity and size. Rarely treated, though sometimes irradiated to create Smokey Quartz.
Special Characteristics
Strongly piezoelectric and pyroelectric; commonly exhibits internal 'rainbows' from fractures or phantom growth lines.
Lore & History
Ancient Greeks believed it was permanent ice. Historically used in divining spheres and as a 'Master Healer' in traditional lore.