Clear Quartz (Rock Crystal)
Quartz var. Rock Crystal · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; Habit is typically hexagonal prisms terminated by two sets of rhombohedrons that form a six-sided pyramid. Often found in prismatic, needle-like, or massive druzy habits.
Mineral Group
Silicates (Subgroup: Tectosilicates)
Chemical Formula
SiO2
Formation Process
Primarily Hydrothermal (crystallizing from hot silica-rich solutions in veins and cavities) or Igneous (magmatic crystallization in pegmatites).
About This Crystal
Colorless and exceptionally transparent. The specimen shows a vitreous (glass-like) luster with long, needle-like prismatic crystals radiating from a central point. Crystals exhibit sharp striations perpendicular to the long axis and smooth, reflective faces.
Physical Characteristics
Color: Colorless; Streak: White; Cleavage: None (Indistinct); Fracture: Conchoidal; Specific Gravity: 2.65; Tenacity: Brittle; Fluorescence: Usually inert but may show weak green or blue under UV.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009 (Uniaxial positive); Dispersion: 0.013; Optically active (rotates polarized light).
Hardness & Durability
Origin Region
Brazil (Minas Gerais), USA (Arkansas), Madagascar, and the Swiss Alps. Found globally in continental crust igneous, metamorphic, and sedimentary rocks.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good (no cleavage); Stability: High stability against chemicals and light; sensitive to sudden thermal shock.
Care & Maintenance
Clean with warm soapy water or ultrasonic cleaners. Safe in sunlight. Storage should be separate from softer stones to prevent scratching them, or harder stones like Topaz/Sapphire to prevent being scratched.
Rarity & Value
Common; Value is determined by clarity, crystal size, and lack of damage to the points. Rock Crystal is generally affordable, though large, clear points or 'phantom' inclusions can increase value.
Special Characteristics
Piezoelectric and pyroelectric properties (generates electricity under pressure or heat change). May contain 'phantom' growth layers or fluid inclusions ('enhydros').
Lore & History
Historically known as 'Krystallos' (frozen ice) by the Greeks. Ancient civilizations used it for carvings and lens-making. In folklore, it is considered a 'master healer' and amplifier of energy and intention.