Quartzite pebble

Hardness: 7 (Mohs scale), Color: Cream, tan, and white, Luster: Vitreous to dull, Crystal structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture)

Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically in orogenic belts. This smooth shape is the result of mechanical weathering in a high-energy water environment (river or beach).

Used in construction, as railway ballast, for decorative landscaping, and occasionally as a source of silica for glass manufacturing.

Quartzite can be older than a billion years; it is so hard that it can scratch steel and glass easily. It is often more resistant to weathering than the surrounding rock types.

Identify in the field by its hardness (it will scratch a knife blade) and its smooth, rounded texture which indicates travel in water. Commonly found in riverbeds and on coastal shorelines.