Smoky Quartz
Quartz var. Smoky Quartz · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal system, typically forming prismatic hexagonal crystals with rhombohedral terminations, often found as massive, tumbled, or raw chunks.
Mineral Group
Silicates, specifically Tectosilicates
Chemical Formula
SiO2
Formation Process
Forms via hydrothermal or igneous processes, particularly in pegmatites and granitic rocks, where natural irradiation of aluminum impurities within the silica lattice creates the characteristic brown to gray coloration.
About This Crystal
A brownish-gray to translucent dark brown raw stone chunk with a vitreous to waxy luster. It exhibits some translucent areas allowing light to pass through, featuring natural surface irregularities and hints of lighter matrix or iron oxide staining on the edges.
Physical Characteristics
Color ranges from light grayish-brown to deep blackish-brown. It has a white streak, conchoidal fracture, no true cleavage, and a specific gravity of approximately 2.65. It is brittle and exhibits piezoelectric and pyroelectric properties.
Optical Properties
Singly refractive optical character (though optically uniaxial positive), with a refractive index of 1.544 to 1.553 and low birefringence of 0.009. Pleochroism is typically weak to moderate in shades of brownish-gray.
Hardness & Durability
Origin Region
Found globally with notable sources in Brazil, Madagascar, the Swiss Alps, and the United States (Colorado). Typically forms in pegmatites and hydrothermal veins.
Hardness & Durability
Mohs hardness of 7, making it durable and suitable for everyday jewelry wear such as rings and pendants, though caution should be exercised against heavy impacts due to brittleness.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid harsh chemical cleaners and prolonged exposure to direct, intense sunlight which may cause the color to fade over time. Store separately to prevent scratching softer stones.
Rarity & Value
Common and widely accessible globally. Value is determined by color saturation, clarity, cut, and size, with deeper, well-formed terminated crystals or large gem-grade rough commanding higher prices. Heat treatment is sometimes used to alter color.
Special Characteristics
Natural irradiation-induced coloration mechanism. Can occasionally feature rutile needles, fluid inclusions, or phantom growth layers within clearer specimens.
Lore & History
Historically used in ancient Scottish jewelry and talismans. In modern crystal healing, it is traditionally associated with the root chakra, grounding energy, releasing stress, and transmutation of negative energies, though these are cultural and traditional beliefs rather than scientific properties.