Limestone
“Built from ancient seas”
Sedimentary
Limestone is a sedimentary rock composed mainly of calcium carbonate, often formed from the accumulated shells and skeletons of marine organisms. Over millions of years, these biological remains compact and cement together into solid rock.
Composition
calcite, aragonite, traces of dolomite
Where Found
The White Cliffs of Dover (England), Florida (USA), Yucatán (Mexico), Croatia
Mohs Hardness
3-4
Fun Fact
The Great Pyramid of Giza was built with roughly 2.3 million limestone blocks, each averaging 2.5 tonnes.
Test Your Knowledge
What happens when dilute hydrochloric acid is dropped onto limestone?
Related Specimens
Want to identify rocks yourself?