Mineral
Smoky Quartz
Silicon dioxide (SiO2)
Hardness: 7 (Mohs scale), Color: light grayish-brown to dark black, Luster: vitreous (glassy), Crystal structure: trigonal, Cleavage: poor/none, Specific gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: light grayish-brown to dark black, Luster: vitreous (glassy), Crystal structure: trigonal, Cleavage: poor/none, Specific gravity: 2.65
Formation & geological history
Forms in igneous and metamorphic rocks, often pegmatites and hydrothermal veins. The smoky color is generated by natural irradiation of aluminum-bearing quartz over millions of years.
Uses & applications
Used in jewelry, decorative items, carving, and as a popular collector's mineral.
Geological facts
Smoky quartz is the national gem of Scotland. Very dark, almost opaque varieties are known as 'morion'. Unlike some gems, its color can fade if exposed to prolonged sunlight and can be altered by heat treatment.
Field identification & locations
Identify by its characteristic smoky brown/gray color, vitreous luster, conchoidal fracture, and hardness of 7 (will scratch glass). Commonly found in Brazil, Madagascar, USA (Colorado), and the Swiss Alps.
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Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock