Smoky Quartz
Quartz var. Smoky Quartz · Semi-Precious Gemstone
Crystal System
Trigonal, shaped into a polished smooth cabochon habit
Mineral Group
Silicates, Tectosilicates
Chemical Formula
SiO2
Formation Process
Hydrothermal and igneous processes where natural irradiation of aluminum impurities within the quartz lattice creates the characteristic brown to gray coloration
About This Crystal
A polished, domed cabochon displaying a translucent to transparent smoky brownish-gray body color with subtle banding and a vitreous to waxy polish luster
Physical Characteristics
Brown to grayish-brown body color with a white streak, conchoidal fracture, no true cleavage, specific gravity of approximately 2.65, and brittle tenacity
Optical Properties
Singly refractive or uniaxial positive with a refractive index of 1.544 to 1.553, weak birefringence, and no significant pleochroism
Hardness & Durability
Origin Region
Found globally with notable sources in Brazil, Madagascar, the US (Colorado), and Switzerland; forms in pegmatites and hydrothermal veins
Hardness & Durability
Mohs hardness of 7, making it durable and suitable for everyday jewelry wear with good resistance to scratching
Care & Maintenance
Clean with warm soapy water and a soft brush, avoid harsh chemicals, and store separately from softer stones; prolonged direct sunlight can cause fading
Rarity & Value
Common and widely accessible, with value depending on color saturation, clarity, and cutting quality, ranging from very affordable to moderate
Special Characteristics
Coloration is caused by natural gamma irradiation acting on trace aluminum impurities substituting for silicon within the crystal structure
Lore & History
Historically used in ancient Scottish jewelry and protective talismans, traditionally associated with grounding, stability, and the root chakra in modern crystal lore