The electrical properties of a material define its behavior when an electric field is applied. The two principal electrical properties are the dielectric constant, which is a measure of the electrical polarization that takes place when an electric field is applied, and the conductivity, which is a measure of the conduction current developed by an electric field.
Materials are classified in a general way as conductors, semiconductors or insulators. A material with a resistivity of 10−5 ohm-meters or less is classed as a conductor; materials with a resistivity greater than 108 ohm-meters are classed as insulators; materials in the intermediate range are semiconductors.
Resistivities which have been reported in the literature for individual materials are listed in Table 26-1. These data were obtained at ambient room temperatures, ranging probably between 15° and 30° C, and at a sufficiently low frequency that these may be classed as D.C. measurements.
The minerals listed in Table 26-1 are all conductors or semiconductors. They are such rarely