Emery, a very hard type of rock with important industrial uses as an abrasive and burnishing agent, is found in abundance on the slopes of Mt. Amomaxis of Naxos, between the villages of Koronos and Apiranthos.
It is dark gray or black in color and mainly consists of corumdum (50%-60%), iron oxides (16%-28%) and other minerals (about 20%). Its corumdum content determines its hardness and, therefore, its quality.
Hardness varies between 7 and 9 on the Mohs scale, where 10 is diamond grade.
Virtually the sum of emery deposits that can be mined in Greece are found on Naxos.
The superior quality of Naxos emery (smirigli in the local dialect) has been known since antiquity.
Its usefulness today is found in applications that require highly anti-slippery properties, such as in tarmac and fire-resistant surfaces, sidewalks, airport runways and loading ramps.
It is also used in the making of emery cloths, boards and discs but it is also found in the form of powder used in polishing and processing metals, stones and glass, in hulling rice and elsewhere.