Smoky Quartz
Quartz var. Smoky Quartz · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal crystal system; displays a prismatic habit with a damaged or partially terminated rhombohedral form
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2 (Silicon Dioxide) with natural irradiation of aluminum-bearing minerals
Formation Process
Magmatic crystallization in pegmatites or hydrothermal veins. The smoky color results from natural gamma radiation during or after formation.
About This Crystal
This specimen is a translucent to opaque smoky quartz fragment. It displays a dark brown to tan color with a vitreous to slightly waxy luster on fractured surfaces. The edges show characteristic quartz conchoidal fracturing and stepped growth.
Physical Characteristics
Color: Brown/tan; Streak: White; Cleavage: None/Indistinct; Fracture: Conchoidal; Specific Gravity: 2.65; Tenacity: Brittle; Fluorescence: Generally inert.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009 (uniaxial positive); Pleochroism: Weak in brownish tones; Dispersion: 0.013; Doubly refractive.
Hardness & Durability
Origin Region
Madagascar, Brazil, Scotland (Cairngorm), Swiss Alps, and the United States (Colorado). Found in pegmatites and metamorphic rocks.
Hardness & Durability
Mohs Hardness: 7; Toughness: Fair/Good; Stability: Generally stable but can fade if exposed to extreme heat (reverting to rock quartz or citrine-like colors).
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid ultrasonic cleansers if internal fractures are present. Store away from intense, direct sunlight to prevent color fading.
Rarity & Value
Common rarity; value is determined by transparency and size. Large, clear crystals from specific locales (like Cairngorm) are more prized. Treatments (irradiation of clear quartz) are very common.
Special Characteristics
Coloration is induced by the presence of trace aluminum and exposure to ionizing radiation within the earth for millions of years.
Lore & History
Historically known as 'Cairngorm' in Scotland and used for clan brooches. Metaphysically, it is traditionally associated with grounding, the root chakra, and neutralizing negative energy.