Smoky Quartz
Quartz var. Smoky Quartz (Silicon Dioxide) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically occurs in hexagonal prisms terminated by rhombohedral faces, often found as massive or tumbled pieces in jewelry.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 (Trace elements of Aluminum and irradiation lead to the characteristic smoky color)
Formation Process
Hydrothermal or Igneous; forms via the crystallization of silica-rich fluids. The smoky color is produced by natural gamma radiation acting on aluminum impurities within the crystal lattice.
About This Crystal
A translucent to nearly opaque variety of quartz. This specific tumbled specimen exhibits a pale, brownish-grey smoky tint with a vitreous (glassy) luster and internal fractures or 'veils'.
Physical Characteristics
Color: Pale brown to grey; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Generally inert, occasionally weak green.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Pleochroism: Weak to moderate in brown shades; Optical Character: Uniaxial (+).
Hardness & Durability
Origin Region
Brazil, Madagascar, Switzerland, and the United States (notably Colorado). Often found in pegmatites and hydrothermal veins.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; Stability: Stable under normal light, but high heat can cause the smoky color to fade or turn yellowish.
Care & Maintenance
Clean with warm soapy water and a soft cloth; avoid ultrasonic cleaners if there are heavy internal fractures. Store away from direct, prolonged sunlight to prevent color fading.
Rarity & Value
Common; very affordable. Value is determined by color uniformity and clarity. Large, eye-clean specimens are abundant and inexpensive.
Special Characteristics
Can contain 'phantom' inclusions where growth stages are visible, or 'enhydro' (water) inclusions. Some specimens show asterism if rutile is present.
Lore & History
Historically used in China for the earliest sunglasses in the 12th century. Metaphysically, it is regarded as a 'grounding stone' associated with the Root Chakra, believed to neutralize negative energy.