Smoky Quartz
Quartz variety Smoky Quartz · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically hexagona prismatic with pyramidal terminations, though shown here in a massive/rough form
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2 (Silicon Dioxide) with natural irradiation of aluminum-bearing impurities
Formation Process
Primary formation occurs in igneous pegmatites and hydrothermal veins under low to moderate temperature conditions.
About This Crystal
This specimen shows a deep brownish-black to translucent gray coloration consistent with smoky quartz. It exhibits a greasy to vitreous luster and a massive, fractured surface with visible inclusions of mica or oxides.
Physical Characteristics
Color: Smoky brown to black; Streak: White; Cleavage: None (indistinct); Fracture: Conchoidal to uneven; Specific Gravity: 2.65; Fluorescence: Generally inert.
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009 (uniaxial positive); Pleochroism: Weak to moderate in brown shades.
Hardness & Durability
Origin Region
Notable sources include Brazil, Switzerland (Swiss Alps), Madagascar, and the United States (Colorado: Pikes Peak).
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; Stability: Stable, though extreme heat may cause color to fade or turn yellow/greenish.
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic cleaners if significant inclusions are present; store away from prolonged direct sunlight.
Rarity & Value
Common rarity; value is determined by transparency and size. Faceted stones are affordable; large museum-grade clusters carry premium prices.
Special Characteristics
Color is produced by natural gamma radiation activating aluminum centers; often found with inclusions like rutile or black tourmaline (schorl).
Lore & History
Historically used in Scotland as 'Cairngorm' for jewelry and dagger handles. Tradition holds it as a grounding stone for protection and neutralizing negative energy.