sedimentary

Siltstone with Fossil Cast

Sedimentary Rock (Siltstone / Fine-grained Sandstone)

AI-generated identification · may be incorrect

Hardness: 3-6 (variable based on cementation); Color: Grayish-brown with tan/yellowish inclusion or fossil impression; Luster: Dull, earthy; Texture: Fine-grained, microcrystalline to clastic.

Hardness: 3-6 (variable based on cementation)
Luster: Dull, earthy

Identified July 27, 2026More sedimentary →

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Physical properties

Hardness: 3-6 (variable based on cementation); Color: Grayish-brown with tan/yellowish inclusion or fossil impression; Luster: Dull, earthy; Texture: Fine-grained, microcrystalline to clastic.

Formation & geological history

Formed through the accumulation and compaction of silt and sand grains in calm water environments like riverbeds, deltas, or shallow marine basins, preserving organic impressions or secondary mineral veins.

Uses & applications

Used primarily for geological study, educational collection, landscaping, and aggregate.

Geological facts

Siltstones often preserve delicate trace fossils, plant casts, or shell molds due to their fine grain size, acting as natural time capsules from ancient aquatic environments.

Field identification & locations

Identified by its fine, smooth texture compared to coarse sandstone, often featuring distinct layers or embedded fossil molds. Found worldwide in sedimentary rock formations.