Emery (rock)

Emery mine on Naxos Island
Corundite from the Naxos emery deposits. The corundum is blue, or sapphire. Wet slab, 10 cm (3.9 in) wide.

Emery, or corundite, is a dark granular rock used to make an abrasive powder. The rock largely consists of corundum (aluminium oxide), mixed with other minerals. Industrial emery may contain a variety of other minerals and synthetic compounds. Crushed or naturally eroded emery (known as black sand) is used as an abrasive. Turkey and Greece are the main suppliers of the world's emery.