sedimentary

Sandstone (River Pebble)

Arenite (SiO2 based)

Hardness: 6-7 Mohs; Color: Tan, beige, or light grey; Luster: Dull/Earthy; Crystal Structure: Clastic (sand grains); Cleavage: None; Specific Gravity: 2.2-2.8

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

Identified May 21, 2026More sedimentary →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 6-7 Mohs; Color: Tan, beige, or light grey; Luster: Dull/Earthy; Crystal Structure: Clastic (sand grains); Cleavage: None; Specific Gravity: 2.2-2.8

Formation & geological history

Formed through the accumulation and cementation of mineral particles or rock fragments (sand) over millions of years. This specific specimen has been rounded into a 'beehive' or 'half-moon' shape by fluvial erosion (water action in a river or stream).

Uses & applications

Used primarily as construction aggregate, for making glass (if high purity silica), and as decorative landscaping stones. Highly rounded pebbles are popular in zen gardens and as pocket stones.

Geological facts

Sandstone makes up about 20-25% of all sedimentary rocks on Earth. The unique shape of this specimen is a result of differential erosion, where softer areas of the rock wore away faster during its time in a moving body of water.

Field identification & locations

Identify in the field by its gritty, sandpaper-like texture and the visible presence of small granules or sand grains. Commonly found in riverbeds, beaches, and desert environments. It will not fizz with acid unless it has a calcitic cement.