sedimentary

Quartz (Orthoquartzite)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale. Color: Pinkish-orange to tan due to iron staining. Luster: Dull to waxy when weathered. Crystal structure: Trigonal/Hexagonal microcrystalline. Specific gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Pinkish-orange to tan due to iron staining
Luster: Dull to waxy when weathered

Identified July 3, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale. Color: Pinkish-orange to tan due to iron staining. Luster: Dull to waxy when weathered. Crystal structure: Trigonal/Hexagonal microcrystalline. Specific gravity: 2.65.

Formation & geological history

Formed from the weathering and transport of silica-rich rocks, later compressed and cemented over millions of years. This specific specimen appears to be a river-tumbled pebble shaped by water erosion.

Uses & applications

Quartzite is used in construction as road ballast and building stone. Small pebbles like this are popular for aquarium gravel, landscape decoration, and beginner rock tumbling.

Geological facts

Quartz is one of the most abundant minerals in Earth's crust. Its hardness allows it to survive long-distance transport in rivers, which is why it is so commonly found as rounded river stones.

Field identification & locations

Identify by its hardness (it should scratch glass) and lack of reaction to acid. Commonly found in riverbeds, beaches, and glacial deposits worldwide.