sedimentary

Conglomerate

Conglomerate (SiO2 matrix with varying clasts)

Hardness: 6.5-7 (if quartz-rich); Color: Grey, tan, with multicolored rounded pebbles; Luster: Dull to earthy; Texture: Clastic, coarse-grained with rounded inclusions; Structure: Massive cementation.

Hardness: 6
Color: Grey, tan, with multicolored rounded pebbles
Luster: Dull to earthy

Identified July 6, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by the lithification of rounded gravel and pebbles, usually in high-energy aquatic environments like riverbeds or shorelines. The location (Denmark/North Sea coast) is consistent with glacial deposits and reworked sea-bed sediments.

Uses & applications

Used as decorative stone, riprap for shoreline protection, and as a material for road base or aggregate in concrete. Historically used as building stone.

Geological facts

Conglomerates are often called 'puddingstone' because they look like raisins or fruit pieces in a pudding. They serve as excellent indicators of ancient river systems and fast-moving water.

Field identification & locations

Identify by looking for smooth, rounded pebbles firmly cemented into a finer-grained matrix. In Denmark, these are often found as glacial erratic pebbles or along coastal beaches.

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Cone-in-cone structure (Limestone)

Cone-in-cone structure (Secondary Sedimentary Structure)

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Chert Breccia

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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