Clear Quartz (Rock Crystal)
Silicon Dioxide var. Rock Crystal · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; Habit is typically hexagonal prisms terminated by rhombohedra, though this specimen is a massive/broken chunk.
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2
Formation Process
Forms primarily in hydrothermal veins and pegmatites through the cooling of silica-rich solutions.
About This Crystal
Transparent to translucent colorless quartz. Exhibits a vitreous (glassy) luster with internal fractures and veils. No distinct crystal faces are present in this rough specimen.
Physical Characteristics
Color: Colorless; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually inert/none.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Optical Character: Uniaxial positive; Dispersion: 0.013.
Hardness & Durability
Origin Region
Found globally; notable sources include Brazil (Minas Gerais), Arkansas (USA), and the Alps (Switzerland).
Hardness & Durability
Mohs Hardness: 7; Toughness: Good (indistinct cleavage); highly durable for all jewelry types.
Care & Maintenance
Very stable. Can be cleaned with warm soapy water, ultrasonic, or steam. Resistant to most household chemicals except hydrofluoric acid.
Rarity & Value
Common; Value is generally low for rough specimens, determined by clarity and size. Rarely treated, though sometimes irradiated to create Smoky Quartz.
Special Characteristics
Piezoelectric and pyroelectric properties. This specimen shows internal 'rainbow' iris effects due to light interference in internal fractures.
Lore & History
Historically known as 'krystallos' (frozen ice) by Greeks. Symbolizes clarity and amplification in traditional folklore and crystal healing practices.