Emery (or corundite) is a dark granular rock used to make abrasive powder. Emery is named after Cape Emeri, Island of Naxos, where it was first discovered. It largely consists of the mineral corundum (aluminium oxide), mixed with other species such as the iron-bearing spinels, hercynite, and magnetite, and also rutile (titania). Industrial emery may contain a variety of other minerals and synthetic compounds such as magnesia, mullite, and silica.
It is black or dark grey in colour, less dense than translucent-brown corundum with a specific gravity of between 3.5 and 3.8. Because it can be a mixture of minerals, no definite Mohs hardness can be assigned: the hardness of corundum is 9 and that of some spinel-group minerals is near 8, but the hardness of others such as magnetite is near 6.
The Greek island of Naxos used to be the main source of this industrially important rock type. It has been mined on the eastern side of Naxos for well over two thousand years until recent times. However, demand for emery has decreased with the development of sintered carbide and oxide materials as abrasives.
|Wikisource has the text of the 1879 American Cyclopædia article Emery.|
- Emery at Mindat.org
- Austin, G. T. (1987). Minerals Yearbook, Volume 1. pp. 71–84.
- Kroschwitz, Jacqueline (2004). Kirk-Othmer encyclopedia of chemical technology (5th ed.). Hoboken, N.J: Wiley-Interscience. p. 10. ISBN 9780471484943.
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|Wikimedia Commons has media related to Emery (mineral).|
- Oberg, Erik; Jones, Franklin D.; Horton, Holbrook L.; Ryffel, Henry H. (2000), Machinery's Handbook (26th ed.), New York: Industrial Press Inc., ISBN 0-8311-2635-3
- CDC - NIOSH Pocket Guide to Chemical Hazards