Clear Quartz (Rock Crystal)
Quartz var. Rock Crystal · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically hexaganol prismatic with pyramidal terminations.
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2
Formation Process
Mostly magmatic in pegmatites or hydrothermal in veins; also forms in metamorphic environments.
About This Crystal
Transparent to translucent colorless crystal. Features a vitreous luster and conchoidal fracture. Often contains internal fractures that create small rainbows.
Physical Characteristics
Color: Colorless. Streak: White. Cleavage: Indistinct/None. Fracture: Conchoidal. Specific Gravity: 2.65. Luminescence: Generally inert or weak.
Optical Properties
Refractive Index: 1.544-1.553. Birefringence: 0.009. Optical character: Uniaxial positive. Often shows internal rainbow interference.
Hardness & Durability
Origin Region
Found globally; notable sources include Brazil (Minas Gerais), Arkansas (USA), and the Alps.
Hardness & Durability
Mohs Hardness: 7. Excellent durability; no cleavage makes it resistant to chipping.
Care & Maintenance
Clean with warm soapy water. Relatively stable but avoid extreme thermal shock. Safe for ultrasonic cleaners if no liquid inclusions.
Rarity & Value
Common rarity. Value is based on clarity and size; generally affordable. High-quality clusters or points are more valued.
Special Characteristics
Contains internal 'rainbows' from thin-film diffraction in internal fractures; exhibits strong piezoelectric and pyroelectric properties.
Lore & History
Known as the 'Master Healer' in traditional lore. Historically used for making crystal balls and decorative vessels since Roman times.