Smoky Quartz
Quartz var. Smoky Quartz (Macro-crystalline) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically prismatic with hexagonal cross-sections, often ending in a six-sided pyramid
Mineral Group
Silicates (Subgroup: Tectosilicate)
Chemical Formula
SiO2 (Silicon Dioxide) with trace Al3+ centers and natural irradiation
Formation Process
Magmatic or Hydrothermal; forms through the slow cooling of silica-rich fluids in cavities. The color is caused by natural gamma radiation activating aluminum impurities.
About This Crystal
A translucent to nearly opaque variety of quartz with a smoky grey, brown, or brownish-black hue. Usually displays a vitreous luster and conchoidal fracture surfaces.
Physical Characteristics
Color: Greyish-brown to black; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually inert.
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009; Pleochroism: Weak to moderate in brown/yellow-brown tones; Uniaxial positive.
Hardness & Durability
Origin Region
Brazil, Madagascar, Switzerland (Alps), and the USA (Colorado and New Hampshire). Found in granitic pegmatites.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; Stability: Very stable, though intense heat (above 200°C) can cause the color to fade or turn yellowish.
Care & Maintenance
Wash with warm soapy water and a soft brush. Avoid ultrasonic cleaners if the stone has liquid inclusions. Store away from direct sunlight to prevent potential fading.
Rarity & Value
Very common; value is based on clarity, size, and depth of color. 'Morion' is the term for very dark, nearly opaque specimens. Generally inexpensive.
Special Characteristics
May contain 'phantom' growth layers or rutile needle inclusions. Can be pleochroic, showing different shades of brown when rotated.
Lore & History
Historically used in China for some of the first sunglasses in the 12th century. In lore, it is considered a 'grounding stone' associated with the Root Chakra and resilience.