sedimentary
Conglomerate
Conglomerate (clastic sedimentary rock)
Hardness: 6.5-7 (variable based on clast types); Color: Tan, brown, gray, and reddish-pink; Luster: Dull/Earthy; Structure: Clastic with rounded grains/pebbles larger than 2mm; Cleavage: None (breaks across pebbles).
- Hardness
- 6
- Color
- Tan, brown, gray, and reddish-pink
- Luster
- Dull/Earthy
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 (variable based on clast types); Color: Tan, brown, gray, and reddish-pink; Luster: Dull/Earthy; Structure: Clastic with rounded grains/pebbles larger than 2mm; Cleavage: None (breaks across pebbles).
Formation & geological history
Formed in high-energy environments such as fast-flowing rivers, alluvial fans, or beaches where water movement rounds rock fragments. Over millions of years, these sediments are buried and lithified with a matrix of sand, silt, or chemical cement (like calcite or silica).
Uses & applications
Commonly used as a decorative stone in construction, a low-grade aggregate for roads, and occasionally as an ornamental stone in landscaping or interior design when polished ('Puddingstone').
Geological facts
Conglomerates are often referred to as 'pudding stones' because they resemble fruit cake or pudding. They are significant because the rounded shape of the pebbles indicates they traveled a long distance from their source.
Field identification & locations
Identify in the field by looking for rounded, water-worn pebbles larger than peas embedded in a finer-grained matrix. Found globally in ancient riverbeds and mountain fronts. Collectors look for unique 'matrix' colors or rare clast compositions.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone (Quartz-rich)
Arenite (SiO2)
sedimentary
Sandstone (with man-made markings)
Arenite (composed primarily of Quartz, SiO2)
sedimentary