mineral

Smoky Quartz

Smoky Quartz (SiO2)

Hardness: 7 on the Mohs scale; Color: Translucent grayish-brown to black; Luster: Vitreous; Crystal Structure: Hexagonal; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.65.

Hardness: 7 on the Mohs scale
Color: Translucent grayish-brown to black
Luster: Vitreous

Identified March 28, 2026More mineral →

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Physical properties

Hardness: 7 on the Mohs scale; Color: Translucent grayish-brown to black; Luster: Vitreous; Crystal Structure: Hexagonal; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.65.

Formation & geological history

Formed in igneous or metamorphic rocks (primarily pegmatites) through the natural irradiation of aluminum-bearing quartz over millions of years. This specimen appears to be a water-worn or tumbled pebble found in secondary alluvial deposits.

Uses & applications

Used widely in lapidary work for gemstones, beads, and carvings. Also used as a grounding stone in metaphysical practices and as decor or collector specimens.

Geological facts

The dark color is caused by natural radiation (from surrounding granite or bedrock) that activates color centers around aluminum impurities. If heated intensely, it can lose its smoky color and turn yellow (citrine-like).

Field identification & locations

Identify by its translucence, brownish-grey smoky tint, and lack of cleavage (it breaks like glass). It is commonly found in mountainous regions such as the Alps, Brazil, and the United States (Colorado).