mineral

Smoky Quartz / Agate Pebbles

Silicon Dioxide (SiO2)

Mohs hardness of 7, vitreous to waxy luster, light brown to amber/smoky translucent color, conchoidal fracture, trigonal crystal structure.

Identified July 25, 2026More mineral →

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Physical properties

Mohs hardness of 7, vitreous to waxy luster, light brown to amber/smoky translucent color, conchoidal fracture, trigonal crystal structure.

Formation & geological history

Formed in silica-rich fluids within igneous cavities, pegmatites, or hydrothermal veins, often weathered out into stream beds and gravels.

Uses & applications

Used primarily as tumbled stones, pocket stones, decorative gravel, and occasionally for simple wire-wrap jewelry.

Geological facts

Quartz is one of the most abundant minerals on Earth's crust, and its colored varieties like smoky quartz or brown chalcedony derive their colors from natural irradiation or microscopic iron impurities.

Field identification & locations

Identified in the field by its hardness (scratches glass), lack of true cleavage, translucent brownish tone, and smooth river-worn or tumbled texture. Common in riverbeds, glacial tills, and gravel deposits worldwide.