Chemically weathered stone
Chemical weathering causes the minerals in rocks to decompose. When the minerals are exposed to water, oxygen, acids and bases or carbon dioxide, they may react, resulting in a change in the overall composition of the rock.
According to Frank Press and Raymond Siever, the authors of “Understanding Earth,” chemical weathering causes some rock minerals to dissolve and others to combine with water and components of the atmosphere, such as oxygen, to form new chemical compounds.
Rocks contain minerals. Some minerals dissolve in acids, bases or water. When rock minerals dissolve, they make the rocks they leave weak and vulnerable to fracture.
It’s through hydrolysis that water is incorporated into a mineral’s chemical structure, turning it into a new mineral. This process turns some minerals, such as feldspar, a key mineral in many rocks, into clay, making it weak and easy to break.
Rusting is a form of oxidation. Iron and other metals are present in many rock minerals. When they oxidize, they decompose, leaving rocks weakened and susceptible to breakage.
Stalactites and stalagmites are made through chemical weathering.