Smoky Quartz
Quartz var. Smoky Quartz (Silicon Dioxide) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically occurs in hexagonal prisms, though this specimen is in a massive or rough fractured state.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 (Trace amounts of Aluminum and natural irradiation responsible for color)
Formation Process
Formation typically occurs in igneous rocks (pegmatites) or hydrothermal veins via crystallization from silica-rich fluids under natural irradiation.
About This Crystal
This is a rough, translucent to sub-opaque specimen with a greyish-brown smoky hue. It displays a vitreous to waxy luster on its fractured surfaces and lacks defined crystal faces in its current state.
Physical Characteristics
Color: Smoky-grey to brown; Streak: White; Cleavage: None (indistinct); Fracture: Conchoidal to uneven; Specific Gravity: 2.65; Fluorescence: Generally inert.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009 (uniaxial positive); Pleochroism: Weak to distinct in darker specimens (brown to reddish-brown).
Hardness & Durability
Origin Region
Globally distributed; notable sources include Brazil, Switzerland (the Alps), USA (Colorado, Arkansas), and Madagascar.
Hardness & Durability
Mohs Hardness: 7.0; Toughness: Good (brittle); Stability: Excellent, though heat can cause the smoky color to fade or turn yellow/green.
Care & Maintenance
Wash with warm soapy water. Avoid ultrasonic cleaners if there are internal fractures. Store away from intense sunlight to prevent color fading over long periods.
Rarity & Value
Common; Value is generally low for rough specimens, determined by color uniformness, clarity, and size. Heat treatment/irradiation is common to darken lighter stones.
Special Characteristics
Piezoelectric and pyroelectric properties; color is created by the natural irradiation of aluminum impurities within the crystal lattice.
Lore & History
Historically used in China for the earliest sunglasses (flat panes) in the 12th century. Traditionally associated with the Root Chakra and grounding/protection in various lore.