sedimentary
Conglomerate
Clastic Sedimentary Rock (Conglomerate)
Hardness: variable (3-7 Mohs); Color: grey to brown; Luster: dull/earthy; Crystal structure: clastic (rounded fragments in a fine-grained matrix); Specific Gravity: 2.1-2.6
- Hardness
- variable (3-7 Mohs)
- Color
- grey to brown
- Luster
- dull/earthy
Identified More sedimentary →
Explore Conglomerate in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: variable (3-7 Mohs); Color: grey to brown; Luster: dull/earthy; Crystal structure: clastic (rounded fragments in a fine-grained matrix); Specific Gravity: 2.1-2.6
Formation & geological history
Formed in high-energy environments like riverbeds or alluvial fans where water currents are strong enough to transport large rounded pebbles, which are then cemented together over geological time.
Uses & applications
Used primarily in the construction industry as coarse aggregate for concrete, as a decorative stone in architecture, and occasionally as a base material for roads.
Geological facts
Conglomerates are often referred to as 'puddingstone' because the rounded clasts resemble raisins in a pudding. They are key indicators of ancient water flow and shoreline positions.
Field identification & locations
Identify by looking for rounded pebbles or cobbles larger than 2mm embedded in a finer matrix of sand or silt. Found globally in ancient riverbeds and mountain fronts.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Cone-in-cone structure (Limestone)
Cone-in-cone structure (Secondary Sedimentary Structure)
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary