Quartz (River Pebble)

Physical Properties

Hardness: 7 on Mohs scale; Color: Milky white to translucent tan; Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal (though rounded by water erosion); Cleavage: None (conchoidal fracture).

Formation & Geological History

Formed through hydrothermal veins or as a primary constituent in igneous rocks like granite. This specific specimen has been rounded and smoothed through fluvial processes in a river or beach environment over thousands of years.

Uses & Applications

Used in landscaping, construction as an aggregate, glass manufacturing, and electronics due to piezoelectric properties. Common specimens are used for decorative aquarium gravel.

Geological Facts

Quartz is the second most abundant mineral in the Earth's continental crust. These rounded pebbles are often called 'river stones' and are highly resistant to chemical and physical weathering.

Field Identification & Locations

Identify by its hardness (it can scratch glass) and lack of cleavage. Found globally in riverbeds, beaches, and glacial deposits. For collectors, look for unique inclusions or clarity.

Identified on: 5/5/2026

Mode: Standard