mineral

Smoky Quartz

Quartz (Silicon Dioxide) - SiO2

Hardness: 7 on the Mohs scale. Color: Brown to black, smoky gray. Luster: Vitreous (glass-like). Crystal structure: Trigonal/Hexagonal prism. Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Hardness: 7 on the Mohs scale
Color: Brown to black, smoky gray
Luster: Vitreous (glass-like)

Identified March 7, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous or metamorphic environments, particularly in pegmatites and hydrothermal veins. The smoky color is caused by natural irradiation of aluminum-bearing silicon dioxide over millions of years.

Uses & applications

Used in gemstone jewelry, ornamental carvings, and metaphysics. Industrially, quartz is used in glassmaking and electronics (piezoelectric properties), though smoky varieties are primarily for aesthetics.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm' after the mountain range. Some extremely dark specimens are almost opaque and are called 'Morion'.

Field identification & locations

Identify in the field by its distinct crystal faces, lack of cleavage, and ability to scratch glass. Commonly found in Brazil, Switzerland, and the USA (Colorado). Look for horizontal striations on the crystal faces.