Emery (mineral)

Emery (also known as iron spinel and hercynite) is a common impure variety of the mineral corundum.

Related Topics:
Mineral - Corundum

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It is black or dark gray in colour, less dense than translucent-brown corundum with a specific gravity of between 3.5 and 3.8 and does not form any regular large-scale crystalline structures. It has a Mohs hardness of 8.

Related Topics:
Specific gravity - Mohs hardness

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In addition to aluminium oxide, emery contains an iron-bearing mineral such as magnetite or hematite and trace impurities such as magnesia, mullite, titania or silica.

Related Topics:
Aluminium oxide - Magnetite - Hematite - Magnesia - Mullite - Titania - Silica

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Crushed or naturally eroded emery (known as black sand) is used as an abrasive.

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