Clear Quartz (Rock Crystal)
Quartz var. Rock Crystal · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically occurs as hexagonal prisms terminated by rhombohedral faces. Form shown is a massive/broken fragment.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2
Formation Process
Hydrothermal or Igneous; forms from cooling silica-rich solutions in veins, cavities, and geodes at varying temperatures.
About This Crystal
A colorless, translucent to transparent specimen with a vitreous (glassy) luster. Shows internal fractures and characteristic conchoidal breaking patterns.
Physical Characteristics
Color: Colorless; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually none.
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009 (Uniaxial positive); No pleochroism.
Hardness & Durability
Origin Region
Found worldwide, notably Brazil, Madagascar, and Arkansas (USA) in hydrothermal veins and pegmatites.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; Highly stable and suitable for all jewelry types.
Care & Maintenance
Clean with warm soapy water; safe for ultrasonic and steam cleaning if no liquid inclusions are present. Avoid hydrofluoric acid.
Rarity & Value
Common; value depends on clarity and size. Abundant globally and usually affordable, though large, clear points command higher prices.
Special Characteristics
Notable for piezoelectricity; some specimens contain 'phantom' growth layers or rutilated/tourmalinated inclusions.
Lore & History
Historically used for seals and carvings in Ancient Egypt and Greece. Traditionally known as the 'Master Healer' in metaphysical practices.