Emery,orcorundite,is a dark granular rock used to make an abrasive powder. The rock largely consists ofcorundum(aluminium oxide), mixed with other minerals. Industrial emery may contain a variety of other minerals and synthetic compounds. Crushed or naturally eroded emery (known asblack sand) is used as anabrasive.Turkey and Greece are the main suppliers of the world's emery.
Description
editEmery is a granular rock used to make an abrasive powder. It largely consists ofcorundum(aluminium oxide), mixed with other minerals such as the iron-bearingspinels,hercynite,andmagnetite,and alsorutile(titania). Industrial emery may contain a variety of other minerals and synthetic compounds such asmagnesia,mullite,andsilica.
Emery is black or dark grey in colour, less dense than translucent-brown corundum with aspecific gravityof between 3.5 and 3.8. Because it can be a mixture of minerals, no definiteMohs hardnesscan 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.
Use
editCrushed or naturally eroded emery (known asblack sand) is used as anabrasive—for example, onemery boardsandemery cloth.It is also used as a traction enhancer inasphaltandtarmacmixtures.
A small quantity of emery is used in coated abrasive products, but its main use in theUnited Statesis wear-resistant floors and pavements.[1]Many tons are shipped to Asia to be used in grinding rice.[2]
Solomon's shamir,a substance used to cut stone during construction of theFirst Temple,was likely emery.[3]
Harvest
editTurkey and Greece are the main suppliers of the world's emery. These two countries produced about 17,500 tons of the mineral in 1987.[4]
The Greek island ofNaxosused 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 as mentioned byPliny the Elder'sThe Natural History,book XXXVII, chp. 32. However, demand for emery has decreased with the development ofsinteredcarbide and oxide materials as abrasives.
Safety
editIn the United States, theOccupational Safety and Health Administrationhas set permissible exposure limits for emery in the workplace:TWA15 mg/m3total exposure and TWA 5 mg/m3respiratory exposure.[5]
See also
editReferences
edit- ^Jacqueline Kroschwitz (2004).Kirk-Othmer encyclopedia of chemical technology(5th ed.). Hoboken, NJ: Wiley-Interscience. p. 10.ISBN9780471484943.
- ^P. Harbin (November 1978).Industrial Minerals.Metal Bulletin: 49–73.
{{cite journal}}:Missing or empty|title=(help) - ^"shamir, shumar and emery".Balashon Hebrew Language Detective.Retrieved13 December2023.
- ^G. T. Austin (1987).Minerals Yearbook, Volume 1.pp. 71–84.
- ^NIOSH Pocket Guide to Chemical Hazards."#0250".National Institute for Occupational Safety and Health(NIOSH).
Further reading
edit- Oberg, Erik; Jones, Franklin D.; Horton, Holbrook L.; Ryffel, Henry H. (2000).Machinery's Handbook(26th ed.). New York: Industrial Press Inc.ISBN0-8311-2635-3.
External links
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