sedimentary

Sandstone (Greywacke/Siltstone variant)

Clastic Sedimentary Rock (composed primarily of Quartz SiO2 and Feldspar)

AI-generated identification · may be incorrect

Hardness: 6-7 Mohs; Color: Tan, grey, or brownish-grey; Luster: Dull/Earthy; Crystal structure: Granular/Clastic; Cleavage: None; Specific gravity: 2.2–2.8

Hardness: 6-7 Mohs
Color: Tan, grey, or brownish-grey
Luster: Dull/Earthy

Identified March 23, 2026More sedimentary →

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Physical properties

Hardness: 6-7 Mohs; Color: Tan, grey, or brownish-grey; Luster: Dull/Earthy; Crystal structure: Granular/Clastic; Cleavage: None; Specific gravity: 2.2–2.8

Formation & geological history

Formed by the accumulation and lithification of mineral particles or rock fragments. These specimens are often rounded 'river stones' shaped by water erosion over hundreds to thousands of years, originating from much older deposits.

Uses & applications

Commonly used as a base material in construction, road fill, and sometimes as 'river rock' for landscaping and decorative garden paths.

Geological facts

Sandstone is one of the most common types of sedimentary rock and can preserve fossils. It is also an important aquifer, as its porosity allows it to hold significant amounts of water or oil underground.

Field identification & locations

Identify in the field by its gritty texture (feels like sandpaper) and rounded edges if found near water. Common globally in riverbeds and coastal areas. Collectors often use them for 'rock painting' hobbies.