sedimentary

Red Siltstone

Siltstone (composed of Quartz and Clay minerals)

AI-generated identification · may be incorrect

Hardness: 6-7 on Mohs scale; Color: Reddish-brown to maroon; Luster: Dull/Earthy; Structure: Clastic; Cleavage: None (conchoidal fracture when fine-grained); Specific Gravity: 2.6

Hardness: 6-7 on Mohs scale
Color: Reddish-brown to maroon
Luster: Dull/Earthy

Identified July 18, 2026More sedimentary →

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Physical properties

Hardness: 6-7 on Mohs scale; Color: Reddish-brown to maroon; Luster: Dull/Earthy; Structure: Clastic; Cleavage: None (conchoidal fracture when fine-grained); Specific Gravity: 2.6

Formation & geological history

Formed through the accumulation and compaction of silt-sized particles in low-energy environments like lake beds or river floodplains. The red color suggests deposition in an oxidizing environment where iron-rich minerals rusted.

Uses & applications

Commonly used as fill material in construction, for landscaping, and occasionally as a source of quartz if pure enough.

Geological facts

Siltstone is intermediate between sandstone and shale. The presence of fine white/greenish veins suggests secondary mineralization, often quartz or calcite, filling old fractures.

Field identification & locations

Identify by its gritty feel (finer than sandstone) and lack of distinct fissility compared to shale. Often found in riverbeds or eroded sedimentary basins.