mineral

Smoky Quartz (Tumbled/Water-worn Quartz)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale. Color: Translucent yellowish-brown to smoky gray-brown. Luster: Vitreous to sub-vitreous. Crystal structure: Trigonal (often found as massive or water-worn pebbles). Cleavage: None, exhibits conchoidal fracture.

Hardness: 7 on Mohs scale
Color: Translucent yellowish-brown to smoky gray-brown
Luster: Vitreous to sub-vitreous

Identified July 25, 2026More mineral →

Explore Smoky Quartz (Tumbled/Water-worn Quartz) in the encyclopedia →

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Physical properties

Formation & geological history

Forms in igneous and metamorphic rocks, such as granites and pegmatites, through hydrothermal processes. The brownish coloration is caused by natural irradiation acting on trace aluminum impurities within the crystal lattice.

Uses & applications

Popular for lapidary work, decorative gemstones, jewelry (beads and cabochons), and crystal collecting.

Geological facts

Smoky quartz is the national gem of Scotland, where it has been mined for centuries in the Cairngorm Mountains and is known as Cairngorm.

Field identification & locations

Can be identified by its hardness (scratches glass readily), absence of cleavage, conchoidal fracturing, and distinctive smoky-brown coloration. Commonly found in stream beds, gravel deposits, and pegmatite pockets worldwide.

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