Smoky Quartz
Quartz var. Smoky Quartz (member of the Quartz group) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; Tumbled specimens (as shown) have lost their original hexagonal prismatic / pyramidal habit
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 with trace inclusions of Aluminum (Al) and natural/artificial irradiation
Formation Process
Igneous/Hydrothermal: Forms as magma cools or from hydrothermal fluids; the 'smoky' color is caused by natural gamma radiation activating aluminum impurities in the lattice
About This Crystal
Transparent to translucent brown-to-gray tinted quartz. These specimens are tumbled/polished, showing a vitreous luster with internal fractures (veils) and small orange-brown iron inclusions
Physical Characteristics
Color: Pale tan to deep chocolate brown. Streak: White. Cleavage: None/Indistinct. Fracture: Conchoidal. Specific Gravity: 2.65. Luster: Vitreous.
Optical Properties
Refractive Index: 1.544-1.553. Birefringence: 0.009. Uniaxial (+). Weak to moderate pleochroism in dark specimens (brown to reddish brown).
Hardness & Durability
Origin Region
Brazil, Madagascar, Switzerland (Alps), and USA (Colorado); found in pegmatites and metamorphic rocks
Hardness & Durability
Mohs Hardness: 7. Excellent durability; lacks cleavage making it resistant to chipping. Suitable for all jewelry types.
Care & Maintenance
Wash with warm soapy water. Stable under most conditions but can fade with prolonged exposure to high heat or direct UV sunlight (loses smoky tint).
Rarity & Value
Common. Value dictated by clarity and depth of color. Low price range. Frequently enhanced by artificial irradiation of clear quartz.
Special Characteristics
Piezoelectric and pyroelectric; shows internal 'rainbows' from light diffraction on internal fractures; may contain phantom crystal growth layers.
Lore & History
Historically used in 12th century China for the first 'sunglasses' (flat panes). Culturally associated with grounding and protection from negative energy in traditional lore.