Boundary Content

the minimum content of a valuable component in a boundary sample of a mineral; the boundary of the part of the deposit that is to be worked—the so-called industrial outline—is determined according to this content. Sometimes the commercial contour is determined by the boundary content of a harmful admixture (for example, the content of ash in brown coal) rather than that of the basic valuable component. In deposits of polymetallic (complex) ores, contouring can be done according to the boundary content of several metals; for nonmetallic minerals, it is done simultaneously according to the boundary content of both the useful and harmful components.