A hard rock mine is a tunnel that is dug into solid rock for the sole purpose of finding valuable or precious rocks, minerals, or metals. Gold originates deep within the earth in places called Pockets. The pockets are filled with gold, heavy ore, and quartz.
Hard rock mines are one of the most effective yet dangerous ways to recover gold. Early hard rock mines were hand dug, and the Chinese were often hired to dig them. Hard rock drifts (horizontal passageways into hillsides) were dug with TNT. The ore was then put into a mining car that was often pulled by burros. Bigger mining companies could afford machines that pulled the mine carts up the passageways. The ore, which consisted of quartz, gold, and other metals was crushed.
The crushed material was moved to a mercury-coated table. The mercury would adhere to the gold and the material that was any less dense than silver would slide right over the mercury. After all this was done, the mercury was superheated and the gold remained. The gold was then turned into gold bars and transferred to the nearest bank by stagecoach.