sedimentary

Sandstone / Weathered Chert

Silicon Dioxide (SiO2) / Quartz-rich Clastic Rock

AI-generated identification · may be incorrect

Hardness: 6-7 on Mohs scale; Color: yellowish-brown, tan, to rusty brownish-gray; Luster: earthy, dull; Grain structure: fine to medium microcrystalline or clastic; Cleavage: none, uneven to sub-conchoidal fracture.

Hardness: 6-7 on Mohs scale
Color: yellowish-brown, tan, to rusty brownish-gray
Luster: earthy, dull

Identified July 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation and cementation of sand-sized mineral grains or silica precipitation in shallow marine, fluvial, or weathering terrestrial environments. Weathered iron oxides give it its characteristic tan to brown tint.

Uses & applications

Commonly used in construction, road base materials, landscaping gravel, and as educational earth science samples.

Geological facts

Weathered rocks with yellow-brown coatings often derive their color from limonite or goethite (iron oxyhydroxide) weathering products forming over millions of years.

Field identification & locations

Identify in the field by its grainy or microcrystalline texture, earthy tan color, and hardness that scratches steel. Commonly found in riverbeds, sedimentary basins, and gravel deposits worldwide.