Smoky Quartz with Feldspar

Physical Properties

Hardness: 6-7 (Mohs), Color: Smoky grey to brownish-tan, Luster: Vitreous to dull, Crystal Structure: Hexagonal (Quartz) / Monoclinic (Feldspar), Cleavage: None (Quartz) to Perfect in two directions (Feldspar)

Formation & Geological History

Formed in granitic pegmatites or hydrothermal veins where silica-rich fluids cool slowly. The smoky color is caused by natural irradiation of trace aluminum during the geological aging process.

Uses & Applications

Used for mineral collecting, metaphysical purposes, and as a source of quartz for industrial glass or electronics. High-grade smoky quartz is used in jewelry.

Geological Facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm.' The grey color is often the result of free silicon formed from the silicon dioxide by natural radiation.

Field Identification & Locations

Identify by its translucent grey 'smoky' appearance combined with the more opaque, blocky tan feldspar. Commonly found in mountainous granitic regions like the Rockies or Alps.

Identified on: 5/11/2026

Mode: Standard