Gangue n. : The mineral or earthy substance associated with metallic ore.

Example:
how can froth flotation be used in separating gold from Gangue?

Taxonomy
gangue, mineral, mining, free encyclopedia, mineral deposit, dumps, commercially viable, degree of separation, search, surrounds, point in time, concentration, tailings, increases, cheaper, copper mines, the 19th century, insecticide.

Defination from the web:
gangue is the commercially worthless material that surrounds, or is closely mixed with, a wanted ore. The separation of the ore from the gangue is a necessary and often significant aspect of mining; it can be a complicated process, depending on ...