Quartzite pebble

Hardness 7 on Mohs scale, pale purple to pinkish-gray hue, dull to vitreous luster, granoblastic metamorphic texture, very durable and resistant to weathering, smooth water-worn river pebble surface

Formed when quartz-rich sandstone is subjected to high heat and pressure during regional metamorphism, fusing quartz grains into a dense crystalline rock. Later eroded and rounded by stream or wave action.

Used in construction as crushed stone, railway ballast, aggregate, and decorative landscaping gravel or river rocks.

Quartzite is so tough that when it breaks, it fractures through the individual quartz grains rather than along the boundaries between them, unlike sandstone.

Identified by its high hardness (scratches glass easily), smooth rounded shape from fluvial transport, and crystalline sugary sparkle when held under bright light. Abundant in riverbeds, glacial tills, and gravel deposits worldwide.