sedimentary
Siltstone with Fossil Cast
Sedimentary Rock (Siltstone / Fine-grained Sandstone)
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
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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.
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