sedimentary

Quartz and Mixed Sedimentary Rocks

Silicon Dioxide (SiO2) mixed with various clastic sedimentary lithologies

AI-generated identification · may be incorrect

Hardness: 7 (for quartz), 3-6 (for others). Color: White, grey, brown, tan. Luster: Vitreous to dull. Structure: Microcrystalline to massive. Cleavage: None (conchoidal fracture common in white pieces).

Hardness: 7 (for quartz), 3-6 (for others)
Color: White, grey, brown, tan
Luster: Vitreous to dull

Identified July 5, 2026More sedimentary →

Explore Quartz and Mixed Sedimentary Rocks in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Likely sourced from a riverbed, glacial till, or crushed gravel deposit. The white specimens are quartz veins precipitated from hydrothermal fluids, while the grey/brown stones are weathered siltstone or sandstone formed by lithification of sediment.

Uses & applications

Commonly used as construction aggregate, landscaping gravel, or road base material. These are standard specimens found in gardens and driveways.

Geological facts

Quartz is one of the most abundant minerals on Earth's crust and is highly resistant to chemical and physical weathering, which is why it often remains as white pebbles while other minerals erode away.

Field identification & locations

Identify in the field by checking for the white stones' inability to be scratched by a steel blade (quartz) and the layered or grainy texture of the darker sedimentary pieces. Commonly found in backyard play areas and drainage pits.