Smoky Quartz
Quartz var. Smoky Quartz (Silicon Dioxide) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically hexaganol prisms with rhombohedral terminations. This specimen shows a massive/broken habit with conchoidal fractures.
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2 (Silicon Dioxide with trace aluminum impurities and natural irradiation)
Formation Process
Igneous/Hydrothermal: Forms from cooling magma or silica-rich fluids. The dark color is caused by natural gamma radiation from surrounding rocks acting on trace aluminum within the crystal lattice.
About This Crystal
A translucent to nearly opaque dark brown to black crystal. This specimen exhibits a vitreous (glassy) luster and significant internal fractures. The edges show characteristic conchoidal (shell-like) fracturing common in quartz.
Physical Characteristics
Color: Smoky brown to black; Streak: White; Cleavage: None (indistinct); Fracture: Conchoidal; Specific Gravity: 2.65; Transparency: Translucent to opaque; Magnetism: None.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009 (Low); Optical Character: Uniaxial positive; Pleochroism: Weak to moderate in brown tones.
Hardness & Durability
Origin Region
Found globally; notable sources include the Swiss Alps, Brazil, Scotland (Cairngorm), and the Pikes Peak region of Colorado, USA. Formed in pegmatites and hydrothermal veins.
Hardness & Durability
Mohs Hardness: 7.0; Toughness: Good (brittle but no cleavage); Stability: Generally high, though intense heat may cause color fading.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid ultrasonic cleaners if there are heavy internal fractures. Store away from direct, prolonged sunlight to prevent potential color fading over many years.
Rarity & Value
Common; Value is determined by transparency and size. Darker, glassy specimens with high clarity are preferred. Treatments: Light quartz is often irradiated to create darker smoky shades synthetically.
Special Characteristics
Displays conchoidal fracture patterns; may contain rutilated inclusions or phantoms in some specimens. This specific piece shows internal rainbow reflections (iridescence) due to light interference in structural cracks.
Lore & History
Historically used in Scotland for jewelry and weaponry (Cairngorm stones). In metaphysical lore, it is considered a grounding stone associated with the Root Chakra, believed to neutralize negative energy and provide emotional stability.