Smoky Quartz
Quartz var. Smoky Quartz · Semi-Precious Gemstone and Mineral Specimen
Crystal System
Trigonal system, typically forming prismatic crystals terminated by six-sided pyramids
Mineral Group
Silicates, specifically the tectosilicate subgroup
Chemical Formula
SiO2 with natural irradiation of aluminum impurities
Formation Process
Forms primarily through igneous and hydrothermal processes where natural radioactive decay from surrounding rocks irradiates aluminum-rich quartz
About This Crystal
Transparent to translucent brown to grayish-black quartz crystal with a vitreous luster, featuring internal fractures and golden-brown iron oxide inclusions
Physical Characteristics
Color ranges from light brownish-grey to deep near-black; white streak; conchoidal fracture; distinct lack of cleavage; specific gravity around 2.65
Optical Properties
Singly or doubly refractive depending on the vibration direction with a refractive index of 1.544 to 1.553, uniaxial positive optical character
Hardness & Durability
Origin Region
Found globally with notable sources in Brazil, Madagascar, Switzerland, and the United States (Colorado)
Hardness & Durability
Mohs hardness of 7, making it durable for general jewelry use with good toughness and stability against normal wear
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid prolonged direct sunlight to prevent fading and keep away from harsh hydrofluoric acid
Rarity & Value
Commonly available worldwide; value depends on clarity, depth of color, and cut, with prices ranging from affordable to moderate for fine polished pieces
Special Characteristics
Often displays natural phantom layers, internal veiling, fracture planes with iron staining, and piezoelectric properties
Lore & History
Historically used in ancient Scottish jewelry and talismans; in modern crystal lore, it is associated with grounding, protection, and the root chakra