mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness of 7 on Mohs scale. Color ranges from light translucent brownish-gray to deep dark smoky black. Vitreous (glassy) luster, hexagonal crystal system, concoidal fracture, no distinct cleavage, specific gravity of 2.65.

Identified July 27, 2026More mineral →

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Physical properties

Formation & geological history

Forms in igneous and metamorphic rocks, particularly pegmatites and alpine-type veins. The distinctive brownish smoky color is produced when natural radiation from surrounding rocks acts on trace aluminum impurities within the clear quartz structure.

Uses & applications

Popular as a gemstone for jewelry, mineral specimen collections, ornamental carvings, and metaphysical/lapidary uses.

Geological facts

Smoky quartz is the national gem of Scotland, where it has been mined for centuries and called 'Cairngorm' after the Cairngorm Mountains. Historically, dark smoky quartz flat crystals were used in 12th-century China to make early sunglasses.

Field identification & locations

Identified by its glass-like clarity, hexagonal prism shapes, hardness (scratches glass), and translucent brownish-smoky tone. Commonly found in Brazil, Madagascar, the Swiss Alps, Russia, and the United States (Colorado, New Hampshire).