Emery stone is a granular metamorphic or igneous rock that is rich in corundum. It is a mixture of oxide minerals, typically corundum, magnetite, spinel and/or hematite. It is the most common form of natural corundum that has been used to manufacture abrasives.

The use of emery as an abrasive has declined significantly in the last several decades. It has been almost completely replaced by manufactured abrasives such as silicon carbide. Silicon carbide has a Mohs hardness of 9 to 9.5. It is inexpensive and usually performs better than natural abrasives made from corundum or emery.