Quartz Pebble (Chalcedony / Quartzite)

Hardness 7 on Mohs scale; waxy to vitreous luster; translucent grayish-white to tan color; conchoidal to sub-conchoidal fracture; no cleavage; specific gravity ~2.65.

Formed through hydrothermal deposition or metamorphic recrystallization, then naturally tumbled and smoothed by river, wave, or glacial action over extended geological time.

Commonly used in lapidary arts for tumbling and cabochons, decorative landscaping, historical stone tool knapping, and as an industrial source of silica.

Quartz is one of the most durable and abundant minerals in the Earth's continental crust. Its high resistance to physical and chemical weathering allows river and beach pebbles to endure long after softer host rocks have eroded away.

Identified in the field by its ability to easily scratch common glass and steel (hardness 7), smooth rounded water-worn exterior, and lack of cleavage planes. Found abundantly in riverbeds, gravel bars, and shorelines worldwide.