Clear Quartz (Rock Crystal)
Quartz var. Rock Crystal · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal (Hexagonal system); typically forms hexagonal prisms terminated by two sets of rhombohedra. This specimen is anhedral/rough.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2
Formation Process
Hydrothermal or Magmatic; crystallizes from silica-rich fluids in environments with high temperatures and cooling rates that allow for crystal growth.
About This Crystal
Transparent to translucent colorless specimen with a vitreous (glassy) luster. Shows internal fractures and incipient rainbow flash (iridescence) due to light interference in internal cracks.
Physical Characteristics
Color: Colorless; Streak: White; Cleavage: None (poor); Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually inert/none; Tenacity: Brittle.
Optical Properties
Uniaxial positive; Refractive Index: 1.544-1.553; Birefringence: 0.009; No pleochroism; Visible internal iridescence/thin-film interference in fractures.
Hardness & Durability
Origin Region
Brazil, Madagascar, Arkansas (USA), and the Alps. Found in igneous pegmatites and hydrothermal vein deposits.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good (lack of cleavage makes it durable); Wearability: Excellent for all jewelry types.
Care & Maintenance
Clean with warm soapy water or ultrasonic cleaners. Generally stable but avoid extreme thermal shock. Resists most chemicals except hydrofluoric acid.
Rarity & Value
Very Common; Value is determined by clarity and size. Abundant worldwide; large specimens are affordable. Treatments like irradiation or coating (aura quartz) are common elsewhere.
Special Characteristics
Displays thin-film interference (rainbow colors) along internal fracture planes. Demonstrates piezoelectricity (generates electric charge under mechanical stress).
Lore & History
Known as the 'Master Healer' in traditional lore. Historically used by Aztecs for carved skulls and by Roman elites as 'frozen ice' (krystallos). Associated with the Crown Chakra.