It depends on where it was and when it happened. Clearly, both individuals and corporate entities met with some success and their efforts occasionally resulted in fortunes. I only have information from NW California, particularly the gold rush in Shasta, Trinity, Humboldt and Siskiyou Counties, California - the northern pink blob on this map. The gold rush here was centered on the Trinity, Klamath and Salmon Rivers following discovery of gold at Reading's Bar (Shasta County) and in Douglas City (Trinity County) by Major Pierson B. Reading in 1848. In the following decade, thousands of prospectors migrated into the region and many were immensely successful. In the first decade of the Gold Rush, mining was done predominately by panning or washing gravel through sluice boxes such as Long Toms or rocker boxes.
Records of early mining in this region suggest that there were many prospectors that became very wealthy using just these primitive methods. White (1930) published the letters of her brother, Franklin A. Buck, a relatively early trader in Weaverville, CA. He, and others, note that a number of the early miners in the region were successful at places like Rich Bar, Cox's Bar, Sailors Bar and other locations using simple placer mining techniques (shoveling gravel into sluice boxes and panning out the fine gold) at the mouths of tributaries to the Trinity and Salmon Rivers. Many of these miners had made their fortunes and left the region by 1852.
Almost immediately, prospectors noted that during significant portions of the year, the gold-bearing gravel was not amenable to mining because there was not sufficient water to wash away gravel. Many began to form "companies", loosely organized groups of miners and laborers to reroute streams via ditches and flumes to the gold bearing locations. About this time miners discovered that rather than shoveling the gravel into sluice boxes they could, given the availability of abundant water, wash gravel from high banks through large sluice boxes using hydraulic nozzles to erode river gravels. By the end of the first few years (mid-1850's) mining companies were seeking outside capital to acquire pipe, nozzles, lumber for flumes and labor for ditch construction and maintenance. This method of placer mining, commonly called "hydraulicking", rapidly came to dominate the industry and many hydraulic miners were very successful. During this period, you see the beginning of corporate mining around the region. For example, the LaGrange mine, established in 1862, required 30 miles of ditches, flumes and pipe to direct water to the gold-bearing material. This was the rise of corporate, industrialized mining and it dominated the industry for decades. Hydraulic placer mining was very successful and persisted into the 1940s.
Following the initial placer mining phase, many technological developments were developed in the 1870s and 1880s. The most lucrative of these entailed hard rock mining - the excavation of mine shafts following gold-rich veins of quartz, and then processing the ores using stamp mills, arrastras and other gold extraction methods. There were many hard rock miners and mining companies that were hugely successful, but like any other aspect of the Gold Rush, there were winners and losers. Hard rock mining by its nature requires significant labor and gold extraction efforts. Many claim holders, as in the case with hydraulic mining noted above, partnered with outside companies in order to gain the capital needed to be successful. Also many mining corporation began to buy up claims throughout the region.
Following the period ending around 1900, placer mining on an enormous scale using hydraulic techniques by mining companies and dredging, also by mining companies, came to dominate the industry. Dredging river bottoms continued until the 1940s, as did "hydraulicking".
In short then, initially, there were many individuals in the early gold rush that struck it rich by panning and sluicing gravels of gold rich bars and stream bottoms. Later, with the formation of mining companies, industrialized mining (hard rock, gargantuan hydraulic mines and dredging) was productive and made owners and stockholders plenty of money. For example, it is thought that the LaGrange mine produced $8 million in gold in the period from 1862 to 1942.
Katherine A. White 1930 A Yankee trader in the gold rush; the letters of Franklin A. Buck. http://www.loc.gov/resource/calbk.067
John Carr 1891 Pioneer Days in California. Times Publishing Company
Alice Goen Jones 1981 Trinity County Historic Sites. Trinity County Historical Society, Weaverville
Valerie Budig-Markin 2004 Nellie E. Ladd - Mining Camp Photographer of the Trinity Alps 1859-1922. Naturegraph
Dewey and Nola Mosier 1983 Tales of the Trinity: writings of Major Horace Bell on his adventures in the Trinity County mining camps in the early 1850s. The articles were first printed in a weekly literary magazine, The Golden Era, in 1879 and 1880. Trinity County Historical Society, Weaverville.
