Quartzite Pebble

Physical Properties

Hardness: 7 on Mohs scale. Color: Tan, brown, and yellowish due to iron oxides. Luster: Vitreous to dull. Crystal structure: Granular/Microcrystalline. Specific gravity: 2.6-2.7. Non-foliated texture.

Formation & Geological History

Formed when quartz-rich sandstone is subjected to high heat and pressure, causing the sand grains to recrystallize. This specific specimen has been rounded into a pebble pebble by water erosion in a river or coastal environment.

Uses & Applications

Large-scale quartzite is used for road ballast, floor tiles, and kitchen countertops. Small pebbles are used in landscaping, aquariums, and as decorative gravel.

Geological Facts

Quartzite is one of the most durable rocks on Earth's surface and is often harder than the steel of a knife blade. It can survive extensive transport in rivers that would wear away softer rocks like limestone.

Field Identification & Locations

Identify by its extreme hardness (cannot be scratched by steel) and lack of reaction to acid. Often found in riverbeds, glacial deposits, and mountain ranges. It has a grainy, sand-like appearance but will break across those grains, unlike sandstone.

Identified on: 4/15/2026

Mode: Standard