sedimentary
Sandstone (Greywacke/Siltstone variant)
Clastic Sedimentary Rock (Lithic Wacke)
Hardness: 6-7 (if silica-rich); Color: Grey, tan, earthy brown; Luster: Dull/Earthy; Crystal structure: Clastic/Granular; Cleavage: None (conchoidal to uneven fracture); Specific gravity: 2.2–2.8
- Hardness
- 6-7 (if silica-rich)
- Color
- Grey, tan, earthy brown
- Luster
- Dull/Earthy
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 (if silica-rich); Color: Grey, tan, earthy brown; Luster: Dull/Earthy; Crystal structure: Clastic/Granular; Cleavage: None (conchoidal to uneven fracture); Specific gravity: 2.2–2.8
Formation & geological history
Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments. This specific rounded specimen likely originated in a high-energy fluvial (river) or glacial environment where erosion smoothed its edges over thousands of years.
Uses & applications
Common varieties are used in construction (crushed stone), decorative landscaping, and historically as building stone or grindstones.
Geological facts
Sandstone contains about 20% of all sedimentary rocks on Earth. The rounded 'cobble' or 'pebble' shape of this piece indicates it has traveled far from its source, likely tumbled by water or ice.
Field identification & locations
Identify by its gritty texture (feels like sandpaper when rubbed) and visible grains. Often found in riverbeds, glacial tills, and coastal areas. It is a fundamental rock for understanding regional depositional history.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
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
sedimentary