The Borax method is a technique of artisanal gold mining, based on the principle that borax reduces the melting point of all minerals, including gold. The melting point of gold is 1063 ℃, which is a much higher temperature than can be obtained by inexpensive burners. By adding borax to the heavy mineral concentrate, the melting point temperature decreases, permitting small-scale miners to melt gold out of their concentrate. By using borax, no mercury flour is produced, hence gold recovery increases.
The borax method of gold extraction has been used by artisanal gold miners in the Benguet area north of Manila in the Philippines for more than 30 years. Some believe it was in practice as early as the 1900s. The method is increasingly being seen as a safe alternative to the widespread use of toxic mercury in artisanal gold mining today. About 30% of the world's mercury emissions comes from small scale mining. Efforts are being made to revive the method and spread its use. Presently around 15,000 artisanal gold miners in a small area of Luzon, the main island in the northern portion of the Philippines, use this method exclusively. The mineral is inexpensive and easily available, and the miners have reportedly found that more gold is recovered through its use.
Watch video of the borax method.