sedimentary

Limestone (River Pebble)

Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 (Mohs scale); Color: light gray to whitish; Luster: matte/earthy; Grain: fine-grained; Reaction: fizzes with dilute hydrochloric acid.

Hardness: 3 (Mohs scale)
Color: light gray to whitish
Luster: matte/earthy

Identified July 14, 2026More sedimentary →

Explore Limestone (River Pebble) in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 3 (Mohs scale); Color: light gray to whitish; Luster: matte/earthy; Grain: fine-grained; Reaction: fizzes with dilute hydrochloric acid.

Formation & geological history

Formed through the accumulation of shell, coral, algal, and fecal debris in marine environments. This specific specimen is a water-worn river pebble, likely transported by glacial or fluvial action from the Northern Limestone Alps.

Uses & applications

Used primarily in construction (crushed stone, cement), agriculture (lime), and as a basic landscaping material.

Geological facts

The coordinates provided (47.8°N, 9.6°E) are in Southern Germany, near Ravensburg. This region is dominated by Molasse deposits and Alpine glacial drift, where limestone pebbles are extremely common river and field finds.

Field identification & locations

Identify by its relative softness compared to quartz (cannot scratch glass) and its rounded shape from water erosion. Common in riverbeds and gravel pits throughout the Alpine foreland.