Electrical properties of minerals

It has long been known to people electrical properties of minerals. The ability of amber is well described to electrify with friction. Native metals, such as copper and silver, are excellent conductors of electricity. And such minerals as calcite or mica, - not less excellent dielectrics. Suffice it to recall marble insulating boards.

It has long been known to people electrical properties of amber is well described to electrify with friction

The magnetic and electrical properties of minerals are closely related to each other. The piezoelectric effect, discovered by the brothers Pierre and Jacques Curie (physicist and mineralogist) in 1880, is characteristic of a number of minerals: tourmaline, nepheline, sphalerite, but it is extremely important that it is superbly displayed in quartz. If pressure is applied to a plate that has been cut from a crystal of rock crystal in a certain way, then opposite electric charges appear on its different sides. And if, on the contrary, to apply variable charges to the plate, it will begin to contract and expand, vibrate, emitting electromagnetic oscillations. Owing to quartz-piezoelectric by geophysicists, the task of searching for ore bodies based on aggregates of quartz grains is solved: the blast wave causes such a body to "respond" to oscillations of the piezoelectric echo.

All minerals with a metallic bond have electrical conductivity. The electrical conductivity of minerals can vary greatly depending on the direction in the crystal (for example, along and across their elongation). Another important quantity determining the electrical properties of minerals is the dielectric constant characterizing their polarization under the action of an electric field. The permittivity of minerals is strongly influenced by various impurities; it is difficult to calculate, and each time it is necessary to measure empirically, as far as possible on the equipment, which allows to standardize the measurement conditions.

For semiconductor minerals, determination of the type of conductivity is very important. Distinguish semiconductors with electronic, hole and mixed conductivity (respectively, n, p and np-semiconductors). The type of conductivity of the same minerals (eg, sulfides - pyrite, arsenopyrite, etc.) often changes regularly in accordance with the vertical or lateral (horizontal - from the center to the flanks) zonality of ore deposits, and its determination can be of considerable help in predicting the behavior of mineralization on the deep horizons and flanks of explored deposits.

The electrical properties of minerals are used for the separation (separation) of minerals in mineralogical analysis, as well as in the industrial enrichment of ores and especially ore concentrates. For this purpose, special devices have been created - separators, electric, magnetic, electromagnetic, in the laboratory and production versions; in the mineralogical analysis hand magnets are also widely used.