Listing description Emery (or corundite) is a dark granular rock used to make abrasive powder. 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 . Detailed description 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. Crushed or naturally eroded emery (known as black sand ) is used as an abrasive — for example, on an emery bo...
Listing description EMERY Man-made emery is a regular aluminum oxide containing a small amount of ferric oxide. This addition gives high durability. Emery is recommended for hand polishing of ferrous and nonferrous materials. Emery (or corundite) is a dark granular rock used to make abrasive powder. 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 . Detailed description 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-gro...