Clear Quartz (Rock Crystal)
Quartz var. Rock Crystal · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically occurs as hexagonal prisms terminated by six-sided pyramids (rhombohedrons). Habit is often prismatic or elongated.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 (Silicon Dioxide)
Formation Process
Primarily hydrothermal, crystallizing from silica-rich fluids in rock fractures at varying temperatures and pressures; also igneous in granite pegmatites.
About This Crystal
Transparent, colorless crystal with a vitreous (glass-like) luster. The specimen shows a clear, elongated form with some internal fractures or veil-like inclusions near the base.
Physical Characteristics
Color: Colorless; Streak: White; Cleavage: None (indistinct); Fracture: Conchoidal; Specific Gravity: 2.65; Tenacity: Brittle; Fluorescence: Generally none.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009 (Uniaxial positive); Dispersion: 0.013; No pleochroism due to lack of color.
Hardness & Durability
Origin Region
Found globally; notable sources include Brazil (Minas Gerais), Arkansas (USA), Madagascar, and the Swiss Alps. Forms in pegmatites and hydrothermal veins.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good (lacks cleavage but can chip); Highly stable and suitable for all types of jewelry.
Care & Maintenance
Safe for cleaning with warm soapy water, ultrasonic cleaners, and steam cleaners. Avoid hydrofluoric acid. Store away from harder stones like Topaz or Diamond.
Rarity & Value
Common; value is determined by clarity and size. Treatments are rare for clear quartz, though it is sometimes irradiated to create Smoky Quartz or coated to create Aura Quartz.
Special Characteristics
Displays piezoelectricity (generates electric charge under pressure). May contain 2-phase inclusions (liquid/gas) or internal 'rainbow' fractures (thin-film interference).
Lore & History
Historically used for hardstone carving and 'crystal balls.' Ancient Greeks believed it was permanently frozen ice (krustallos). Traditionally associated with the Crown Chakra and thought to 'amplify energy.'