Smoky Quartz
Quartz var. Smoky (Silicon Dioxide) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically prismatic with hexagonal cross-sections, often terminated by two rhombohedra.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 (Aluminum impurities + Ionizing radiation)
Formation Process
Igneous and Hydrothermal. Often forms in pegmatites and quartz veins under low to moderate temperatures where natural radiation from surrounding rocks affects aluminum impurities.
About This Crystal
A translucent to transparent variety of quartz ranging from pale grayish-tan to deep brownish-black (Morion). Possesses a vitreous luster and frequently contains internal fractures or 'veil' inclusions.
Physical Characteristics
Color: Smoke-grey to brownish-black. Streak: White. Cleavage: Indistinct/Poor. Fracture: Conchoidal. Specific Gravity: 2.65. Luminescence: Generally inert.
Optical Properties
Refractive Index: 1.544–1.553. Birefringence: 0.009. Pleochroism: Weak (shades of brown). Uniaxially positive.
Hardness & Durability
Origin Region
Brazil, Switzerland (Swiss Alps), USA (Mount Antero, Pike's Peak), Madagascar, and Scotland (Cairngorms).
Hardness & Durability
Mohs Hardness: 7. Excellent durability and toughness for jewelry use, though internal inclusions can create weak points.
Care & Maintenance
Safe to clean with warm soapy water and ultrasonic cleaners. Avoid prolonged exposure to intense sunlight as the color can fade back to clear quartz.
Rarity & Value
Common. Value is determined by transparency, evenness of color, and crystal size. Often undergoes heat treatment to improve clarity or irradiation to darken light clear quartz.
Special Characteristics
Pleochroism is visible in darker specimens. Some may exhibit 'phantom' growth layers or rutilated inclusions (Rutilated Smoky Quartz).
Lore & History
Historically known as 'Cairngorm' in Scotland and used in jewelry for kilts and sgian-dubhs. Metaphysically associated with grounding, protection, and the Root Chakra.