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The name "corundum" is derived from the Tamil-Dravidian word kurundam (ruby-sapphire) (appearing in Sanskrit as kuruvinda). [8] [9] Because of corundum's hardness (pure corundum is defined to have 9.0 on the Mohs scale), it can scratch almost all other minerals.
The Mohs scale is an ordinal scale. For example, corundum (9) is twice as hard as topaz (8), ... The Mohs scale hardness of minerals can be commonly found in ...
The Mohs Hardness Scale is the main scale to measure mineral hardness. Finger nail is 2.5, copper coin is 3.5, glass is 5.5 and steel is 6.5. Hardness scale is Talc is 1, Gypsum is 2, Calcite is 3, Fluorite is 4, Apatite is 5, Orthoclase Feldspar is 6, Quartz is 7, Topaz is 8, Corundum is 9 and Diamond is 10. Odor; Not always recommended.
Vickers hardness test; Brinell scale This page was last edited on 16 November 2024, at 12:16 (UTC). Text is available under the Creative Commons ...
Emery 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.
Because of corundum's hardness (pure corundum is defined to have 9.0 on the Mohs scale), it can scratch almost all other minerals. It is commonly used as an abrasive on sandpaper and on large tools used in machining metals, plastics, and wood. Emery, a variety of
Aluminium oxide is used for its hardness and strength. Its naturally occurring form, corundum, is a 9 on the Mohs scale of mineral hardness (just below diamond). It is widely used as an abrasive, including as a much less expensive substitute for industrial diamond. Many types of sandpaper use aluminium oxide crystals.
Adamantine spar is a silky brown variety of corundum. It has a hardness of 9 on the Mohs scale. [1] See also. Yogo sapphire; References This page was last edited ...