Clear Quartz (Rock Crystal)
Quartz var. Rock Crystal · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically prismatic with pyramidal terminations and horizontal striations on prism faces.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2
Formation Process
Hydrothermal; commonly forms in veins, pegmatites, and geodes from cooling silica-rich fluids under high pressure.
About This Crystal
Colorless and transparent mineral with a vitreous (glassy) luster. Shows internal fractures, conchoidal surfaces, and cloudiness in some areas.
Physical Characteristics
Color: Colorless; Streak: White; Cleavage: Poor/Indistinct; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually none; Piezoelectric.
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009 (Uniaxial positive); No pleochroism or dispersion is significant in colorless varieties.
Hardness & Durability
Origin Region
Brazil, Madagascar, Arkansas (USA), and the Swiss Alps are notable sources for high-quality specimens.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; Stability: Stable to light and chemicals, though sensitive to thermal shock.
Care & Maintenance
Safe to clean with warm soapy water or ultrasonic cleaners. Highly durable but should be stored away from harder stones like Topaz or Sapphire.
Rarity & Value
Common; Value is determined by transparency, lack of internal inclusions, and crystal size. Generally affordable and rarely treated if colorless.
Special Characteristics
Piezoelectric and pyroelectric properties. Can contain 'phantom' inclusions or 'enhydro' water bubbles in rare specimens.
Lore & History
Historically used for seals and carvings in Ancient Greece and Rome. Traditional beliefs refer to it as a 'Master Healer' stone, associated with the Crown Chakra.