sedimentary

Sandstone (Tumbled/River Pebble)

Arenite (composed primarily of SiO2)

Hardness: 6-7 (if silica-cemented); Color: Tan, beige, and cream with concentric banding; Luster: Dull/Earthy to slightly waxy; Structure: Clastic, fine-grained; Cleavage: None; Specific Gravity: 2.2-2.8

Hardness: 6-7 (if silica-cemented)
Color: Tan, beige, and cream with concentric banding
Luster: Dull/Earthy to slightly waxy

Identified May 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments. The banding often represents changes in mineral content or water chemistry during deposition. These are found in riverbeds, coastal areas, and deserts.

Uses & applications

Used primarily as decorative stones, landscaping material, or 'worry stones'. In larger quantities, sandstone is a critical construction material for buildings and paving.

Geological facts

The circular banding seen here is often called Liesegang rings, which are secondary sedimentary structures formed by the precipitation of minerals from fluid in the pore spaces of the rock.

Field identification & locations

Identify by its gritty texture (if unpolished) and visible layering. It is ubiquitous in sedimentary basins worldwide. For collectors, look for unique patterns or 'picture rock' qualities.

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Arenite (if sandstone)

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Cone-in-cone structure (Secondary Sedimentary Structure)

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Brecciated Chert (Microcrystalline Silica)

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Sandstone Grain

Clastic Sedimentary Rock Grain (SiO2 dominated)

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Shale or Slaty Mudstone

Argillaceous sedimentary rock

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Sandstone

Arenite (primarily SiO2)

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