Orange Quartzite / River Pebble

Physical Properties

Hardness: 7 (Mohs scale), Color: Orange to reddish-tan due to iron oxide impurities, Luster: Vitreous to waxy, Crystal Structure: Hexagonal (microcrystalline), Cleavage: Indistinct/Conchoidal fracture, Specific Gravity: 2.6-2.7

Formation & Geological History

Formed through the metamorphism of quartz-rich sandstone. Under intense heat and pressure, original quartz grains recrystallize and fuse together. This specific specimen has likely been smoothed and rounded by water action in a river or coastal environment.

Uses & Applications

Commonly used as decorative gravel, in landscaping, as a construction aggregate, or polished as a tumble stone for beginner collectors. Large-scale quartzite is used for countertops and floor tiles.

Geological Facts

Quartzite is so hard that it will scratch glass. It is often confused with marble, but unlike marble, it does not react (fizz) with acid. The orange color is often caused by 'iron staining' where hematite or limonite fills the spaces between grains.

Field Identification & Locations

Identify by its extreme hardness and the fact that it breaks through the quartz grains rather than around them. It is commonly found in riverbeds, glacial tills, and mountainous regions worldwide. Collectors should look for smoothness and color vibrancy.

Identified on: 4/13/2026

Mode: Standard