Gravity concentration remained the dominant mineral processing method for two thousand years, and it is only in the twentieth century that its importance has declined, with the development of such processes flotation, magnetic separation and leaching. Gravity concentration works best for rich ores, for those showing a coarse size of liberation, for placer deposits, for pre-concentration, and for processing in remote areas or where the situation dictates the least expenditure of money. Today, gravity concentration is used for the treatment, not of one or two minerals, but for a diverse range; from andalusite to zircon, from coal to diamonds, from mineral sands to metal oxides and from industrial minerals to precious metals.