Smoky Quartz

Physical Properties

Hardness: 7 (Mohs scale); Color: Gray, brownish-black, to translucent smoky yellow; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (Trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific Gravity: 2.65.

Formation & Geological History

Formed in igneous or metamorphic rocks (especially pegmatites) through the slow cooling of silica-rich hydrothermal solutions or magma. The 'smoky' color comes from natural irradiation of aluminum impurities within the crystal lattice.

Uses & Applications

Used in jewelry (faceted or cabochon), ornamental carvings, and as a popular specimen for collectors. Historically used for early sunglasses in China and in modern metaphysical practices.

Geological Facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm' because it is found in the Cairngorm Mountains. Extremely dark, opaque smoky quartz is often called 'Morion'.

Field Identification & Locations

Identify in the field by its distinct smoky translucency and hexagonal crystal faces. It will scratch glass easily but cannot be scratched by a steel knife. Common in granitic terrains and mountain ranges worldwide.

Identified on: 4/23/2026

Mode: Standard