A large number of minerals exhibit anisotropic surface properties. This include the inherently hydrophobic molybdenite (sulfide) and talc (magnesium silicate), the clays (aluminum silicates), and several fibrous minerals such as chrysotile. Some of these, e.g. molybdenite in the flotation of Cu-Mo sulfide ores, are valuable. Others form a troublesome gangue: talc in the flotation of platinum ores, clays in the flotation of many ores, and chrysotile in the flotation of Ni sulfide ores.The particle-to-bubble attachment is affected by mineral wettability and electrical charge. Flotation studies therefore commonly include the tests aimed at detennining collector adsorption and the surface charge at the mineral/water interface. In case of isotropic minerals, all sides of the crystal are created by breaking the same bonds with resulting mineral surfaces being homogeneous and having identical electrical charge. This is the case of quartz. The new surfaces formed when larger pieces of quartz are crushed are created by breaking identical Si-0 bonds. As a result all the new quartz surfaces have the same composition.
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