Smoky Quartz
Quartz var. Smoky (Silicon Dioxide) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically hexoganol prisms or massive/granular forms
Mineral Group
Silicates (Subgroup: Tectosilicates)
Chemical Formula
SiO2 (with trace Al impurities and natural irradiation)
Formation Process
Igneous and Hydrothermal; often forms in pegmatites and hydrothermal veins under low to moderate temperatures.
About This Crystal
A translucent to nearly opaque variety of quartz ranging from light grayish-brown to deep black. It features a vitreous to greasy luster and a grainy, sugary texture in weathered or massive specimens like the one pictured.
Physical Characteristics
Color: Smoky gray to dark brown; Streak: White; Fracture: Conchoidal to uneven; Specific Gravity: 2.65; Fluorescence: Generally inert.
Optical Properties
Refractive Index: 1.544–1.553; Uniaxial (+); weak pleochroism in darker specimens; no significant dispersion.
Hardness & Durability
Origin Region
Worldwide; notable sources include Brazil, Switzerland (Alps), and USA (Arkansas and Colorado).
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; very durable for most jewelry and handling though internal fractures can weaken it.
Care & Maintenance
Safe to clean with warm soapy water; avoid prolonged exposure to direct high-intensity sunlight as color can rarely fade; avoid thermal shock.
Rarity & Value
Common; value depends on clarity and color depth. Heavily included or massive/granular pieces like the sample have low monetary value.
Special Characteristics
The smoky color is caused by the presence of aluminum substituting for silicon in the lattice, combined with exposure to natural gamma radiation.
Lore & History
Historically used in China for early sunglasses (12th century). Traditionally associated with grounding, protection from negative energy, and the Root Chakra in crystal healing lore.