Smoky Quartz
Quartz var. Smoky Quartz · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically found in hexagonal prismatic habits but appears massive or sub-conchoidal in this rough fragment
Mineral Group
Silicates (Tectosilicates)
Chemical Formula
SiO2 (Silicon Dioxide) with trace inclusions of Aluminum (Al) and natural irradiation
Formation Process
Magmatic or Hydrothermal; forms through the cooling of silica-rich fluids. The 'smoky' color is caused by natural gamma radiation activating aluminum impurities within the crystal lattice.
About This Crystal
The specimen is a rough, translucent to sub-opaque fragment exhibiting a grayish-brown to charcoal 'smoky' hue. It shows a vitreous to greasy luster on fresh surfaces and lacks well-defined external crystal faces.
Physical Characteristics
Color: Smoky brown to black; Streak: White; Cleavage: None; Fracture: Conchoidal to uneven; Specific Gravity: 2.65; Fluorescence: Generally inert; Tenacity: Brittle.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Optical Character: Uniaxial positive; Pleochroism: Weak to distinct in brownish tones.
Hardness & Durability
Origin Region
Notably sourced from Brazil, Madagascar, Switzerland (Alps), and the USA (Colorado). Commonly found in granite pegmatites and hydrothermal veins.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; Stability: Stable under most conditions, though deep color can occasionally fade if exposed to extreme heat or prolonged direct UV light.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid ultrasonic cleaners if internal fractures are present. Store away from harder stones like Topaz or Sapphire to prevent scratching.
Rarity & Value
Common; generally affordable. Value increases with transparency, 'morion' (near-black) depth of color, and lack of internal fractures. Naturally smoky quartz is more valued than irradiated clear quartz.
Special Characteristics
Exhibits natural irradiation-induced color centers. Rough specimens often show conchoidal (shell-like) fracture patterns typical of silica minerals.
Lore & History
Historically used in Scotland as 'Cairngorm' for highland dress ornamentation. Traditionally associated with grounding and protection in folklore; believed to transform negative energy into positive stability.