Smoky Quartz
Quartz var. Smoky (IMA-approved species: Quartz) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically hexagona-prism habit with pyramidal terminations, though shown here in a massive, fractured form
Mineral Group
Silicates (Tectosilicates)
Chemical Formula
SiO2 (Silicon Dioxide) with trace Aluminum (Al3+) and natural irradiation
Formation Process
Forms via magmatic or hydrothermal processes where natural background radiation from surrounding rocks acts on trace aluminum within the quartz structure to produce the dark color
About This Crystal
Translucent to nearly opaque dark brown or grayish-black quartz. This specimen shows a vitreous to greasy luster with significant conchoidal fracturing and a somewhat 'smoky' appearance
Physical Characteristics
Color: Smoky brown to black; Streak: White; Cleavage: None/Indistinct; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually inert
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009; Uniaxial (+); Pleochroism: Weak to moderate in dark specimens (brown to reddish-brown)
Hardness & Durability
Origin Region
Notably sourced from Brazil, Madagascar, Switzerland (Alps), and the USA (Pikes Peak, Colorado); typically found in pegmatites and hydrothermal veins
Hardness & Durability
Mohs Hardness: 7; Toughness: Good (no cleavage); Stable under most conditions but can fade if exposed to extreme heat (over 200°C)
Care & Maintenance
Wash with warm soapy water; avoid ultrasonic cleaners if many internal fractures are present; store away from prolonged direct sunlight to prevent potential fading
Rarity & Value
Common; Value is determined by transparency and size; deep 'Morion' (black) varieties are highly sought after by collectors; generally affordable price range
Special Characteristics
May contain 'phantom' growth layers or rutilated inclusions; the dark color is a result of natural or artificial irradiation of aluminum-bearing quartz
Lore & History
Historically used in 12th-century China to make the first 'sunglasses'; traditionally associated with grounding, detoxification, and the root chakra in metaphysical practices