Quartz pebble

Hardness of 7 on the Mohs scale, typically white, clear, or yellowish due to weathering, vitreous to greasy luster, hexagonal crystal system when unweathered, conchoidal fracture with no true cleavage, specific gravity around 2.65.

Formed through the mechanical and chemical weathering of parent igneous or metamorphic rocks containing quartz. Due to its extreme resistance to weathering and abrasion, quartz frequently survives long transportation in rivers and streams, becoming rounded pebbles deposited in sedimentary environments such as riverbeds, beaches, and conglomerates.

Used primarily as decorative aggregate, in landscaping, aquarium substrates, and occasionally polished for lapidary crafts or tumbled stones.

Quartz is one of the most abundant and durable minerals in Earth's continental crust. Because it does not easily break down chemically or physically, quartz pebbles are ubiquitous geological markers of ancient river systems and shorelines.

Can be identified easily in the field by its high hardness (scratches glass), lack of cleavage, and conchoidal fracture. Commonly found worldwide in stream beds, gravel bars, and sedimentary formations.