Smoky Quartz
Quartz var. Smoky Quartz (Silicon Dioxide) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically occurs as hexagonal prisms terminated by rhombohedrons, often found in massive or druzy habits
Mineral Group
Silicates; Tectosilicate subgroup
Chemical Formula
SiO2 (with trace Al3+ ions and natural radiation exposure)
Formation Process
Igneous and Hydrothermal; formed through the crystallization of silica-rich fluids. The dark color is induced by natural gamma radiation from surrounding rocks acting on aluminum impurities
About This Crystal
A translucent to nearly opaque variety of quartz ranging from pale grey to deep brownish-black (Morion). It exhibits a vitreous luster and conchoidal fracture patterns
Physical Characteristics
Color: Brownish-grey to black; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually inert
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009 (uniaxial positive); Pleochroism: Weak to distinct in dark specimens (brown to reddish-brown)
Hardness & Durability
Origin Region
Global; notable sources include Brazil, Switzerland (Alpine clefts), USA (Colorado), and Madagascar; commonly found in granite pegmatites
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; Stability: Stable, but may fade if exposed to extreme heat (over 200-300°C) or prolonged intense UV
Care & Maintenance
Wash with warm soapy water; safe for ultrasonic cleaners. Store away from harder stones like Topaz or Sapphire to prevent scratching
Rarity & Value
Common; value is determined by transparency and size. Darker 'Morion' and 'Cairngorm' varieties are prized; often heat-treated to produce Citrine
Special Characteristics
May contain rutilated inclusions or phantoms; exhibits piezoelectricity; black variety is known as Morion
Lore & History
Used in Ancient China for early sunglasses; traditionally associated with grounding and detoxification in folklore; national gem of Scotland (Cairngorm stone)