Smoky Quartz
Quartz var. Smoky Quartz (IMA: Quartz) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically occurs in hexagonal prisms with pyramidal terminations; this specimen is world-worn or tumbled (massive/alluvial)
Mineral Group
Silicates; Tectosilicate subgroup
Chemical Formula
SiO2 (Silicon Dioxide) with aluminum impurities and natural radiation
Formation Process
Igneous and Metamorphic; typically forms in pegmatites or hydrothermal veins where natural radiation from surrounding rocks acts on aluminum trace elements
About This Crystal
Transparent to translucent grayish-brown to black color. This specimen is a rounded, tumbled pebble with a vitreous (glassy) luster and smooth surface texture.
Physical Characteristics
Color: Smoky brown; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually inert; Piezoelectric and pyroelectric.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Optical Character: Uniaxial (+); Pleochroism: Weak to distinct in shades of brown.
Hardness & Durability
Origin Region
Brazil, Switzerland (Alpine 'Gwindels'), Scotland (Cairngorms), and various locations in the USA (Pikes Peak, Colorado)
Hardness & Durability
Mohs Hardness: 7; Toughness: Good (slightly brittle); Excellent durability for jewelry; no cleavage makes it resistant to splitting.
Care & Maintenance
Wash with warm soapy water; safe for ultrasonic and steam cleaning unless there are fractures. Avoid high heat to prevent color fading; store separately to avoid scratching softer stones.
Rarity & Value
Common; Value is determined by transparency and intensity of color. High-quality natural specimens are affordable; rarely treated, though irradiation can darken light stones.
Special Characteristics
Natural irradiation causes color; can contain inclusions like rutile needles or phantoms; exhibits conchoidal fracture patterns on unpolished surfaces.
Lore & History
Historically used in China for the earliest sunglasses (flat panes) in the 12th century. Metaphysically associated with grounding, protection, and clearing negative energy (root chakra).