A gold rush is a period of feverish migration of workers into the area of a dramatic discovery of commercial quantities of gold. Eight gold rushes took place throughout the 19th century in Argentina, Australia, Brazil, Canada, Chile, New Zealand, South Africa, and the United States.

Gold rushes were typically marked by a general buoyant feeling of a "free for all" in income mobility, in which any single individual might become abundantly wealthy almost instantly. The significance of gold rushes in history has given a longer life to the term, and it is now applied generally to denote any capitalist economic activity in which the participants aspire to race each other in common pursuit of a new and apparently highly lucrative market, often precipitated by an advance in technology.facts: date=March 2008

Gold rushes helped spur permanent non-indigenous settlement of new regions and define a significant part of the culture of the North American and Australian frontiers. As well, at a time when money was based on gold, the newly-mined gold provided economic stimulus far beyond the gold fields. Gold rushes presumably extend back as far as gold mining, to the Roman Empire, whose gold mining was described by Diodorus Siculus and Pliny the Elder, and probably further back to Ancient Egypt and Saudi Arabia.

Life cycle of a gold rush

The rush is often started by a discovery of placer gold made by an individual or small group. At first the gold may be washed from the sand and gravel by individual miners with little training, using a gold pan or similar simple instrument. Once it is clear that the volume of gold-bearing sediment is larger than a few cubic meters, the placer miners will build rockers or sluice boxes, with which a small group can wash gold from the sediment many times faster than using gold pans. (See placer mining for details.) Winning the gold in this manner requires almost no capital investment, only a simple pan or equipment that may be built on the spot, and only simple organization. The low investment, the high value per unit weight of gold, and the ability of gold dust and gold nuggets to serve as a medium of exchange, allow placer gold rushes to occur even in remote locations.

After the sluice-box stage, placer mining may become increasingly large scale, requiring larger organizations, and higher capital expenditures. Small claims owned and mined by individuals may need to be merged into larger tracts. Difficult-to-reach placer deposits may be mined by tunnels. Water may be diverted by dams and canals to placer mine active river beds or to deliver water needed to wash dry placers. The more advanced techniques of ground sluicing, hydraulic mining, and dredging may be used.

Typically the heyday of a placer gold rush would last only a few years. The free gold supply in stream beds would become depleted somewhat quickly, and the initial phase would be followed by prospecting for veins of lode gold that were the original source of the placer gold. Hardrock mining, like placer mining, may evolve from low capital investment and simple technology to progressively higher capital and technology. The surface outcrop of a gold-bearing vein may be oxidized, so that the gold occurs as native gold, and the ore needs only to be crushed and washed (free milling ore). The first miners may at first build a simple arrastre to crush their ore; later, they may build stamp mills to crush ore more quickly. As the miners dig down, they may find that the deeper part of vein contains gold locked in sulfide or telluride minerals, which will require smelting. If the ore is still sufficiently rich, it may be worth shipping to a distant smelter (direct shipping ore). Lower-grade ore may require on-site treatment to either recover the gold or to produce a concentrate sufficiently rich for transport to the smelter. As the district turns to lower-grade ore, the mining may change from underground mining to large open-pit mining.