Clear Quartz (Rock Crystal)
Quartz (Alpha Quartz) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically hexaganol prisms terminated by two rhombohedra
Mineral Group
Silicates (Tectosilicates)
Chemical Formula
SiO2
Formation Process
Hydrothermal; forms in veins and pegmatites from silica-rich solutions at a wide range of temperatures
About This Crystal
Transparent, colorless crystal with a vitreous luster. This specimen appears as a prismatic fragment with visible internal fractures and faint cloudy inclusions near the base.
Physical Characteristics
Colorless, white streak, none-to-poor cleavage, conchoidal fracture, specific gravity of 2.65, non-fluorescent under UV
Optical Properties
Refractive index 1.544-1.553, low birefringence (0.009), uniaxial positive, no pleochroism
Hardness & Durability
Origin Region
Global; notable sources include Brazil (Minas Gerais), Arkansas (USA), and Madagascar
Hardness & Durability
Mohs hardness 7.0; high durability and toughness; stable against light and most chemicals
Care & Maintenance
Wash with warm soapy water; safe for ultrasonic cleaners; avoid hydrofluoric acid
Rarity & Value
Very Common; low price point; value determined by clarity and size; rarely treated when colorless
Special Characteristics
Piezoelectric and pyroelectric properties; contains internal 'veils' or fractures that create rainbow reflections
Lore & History
Ancient Greeks believed it was permanently frozen ice (krystallos); widely used as a 'master healer' in modern crystal lore