Smoky Quartz
Quartz var. Smoky Quartz (Silicon Dioxide) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal (Hexagonal system); as a tumbled stone, it lacks original crystal faces but naturally forms as hexagonal prisms with pyramidal terminations.
Mineral Group
Silicates (Tectosilicate group)
Chemical Formula
SiO2 (Silicon Dioxide) with trace amounts of aluminum and natural irradiation from surrounding minerals.
Formation Process
Igneous/Hydrothermal. Forms through the crystallization of silica-rich fluids. The dark color is induced by natural gamma radiation from the surrounding environment acting on aluminum impurities within the crystal lattice.
About This Crystal
A translucent to transparent brownish-grey to black colored quartz. This tumbled specimen shows a vitreous (glassy) luster and uneven color distribution (color zoning) typical of natural smoky quartz.
Physical Characteristics
Color: Smoky brown to nearly black. Streak: White. Cleavage: None (poor). Fracture: Conchoidal. Specific Gravity: 2.65. Fluorescence: Usually inert/none. Transparency: Translucent to transparent.
Optical Properties
Refractive Index: 1.544–1.553. Birefringence: +0.009. Pleochroism: Weak to distinct in dark specimens (brown to reddish-brown). Optically Uniaxial (+).
Hardness & Durability
Origin Region
Brazil, Madagascar, USA (Colorado/New Hampshire), Switzerland (Alps), and Scotland (Cairngorm Mountains). Found in pegmatites and hydrothermal veins.
Hardness & Durability
Mohs Hardness: 7. Toughness: Good (highly durable). Stability: Stable to light, but can lose color if exposed to extreme heat (over ~200-300°C).
Care & Maintenance
Clean with warm soapy water and a soft brush. Ultrasonic and steam cleaning are generally safe unless there are heavy inclusions. Keep away from intense heat sources to prevent color fading.
Rarity & Value
Common. Value factors include clarity, depth of color, and size. Very dark specimens (Morion) are highly prized. Lab-irradiated quartz is common and can be difficult to distinguish from naturally irradiated specimens.
Special Characteristics
May contain internal veils or wispy inclusions. Very dark, nearly opaque varieties are known as 'Morion'. When found in the Cairngorm Mountains of Scotland, it is known as 'Cairngorm stone'.
Lore & History
Historically used in the 12th century for the first sunglasses in China (made of flat smoky quartz panes). In traditional lore, it is considered a 'grounding stone' associated with the Root Chakra, believed to neutralize negative energy.