…as to the cause which so suddenly and so largely raised wages in California in 1849, and in Australia in 1852. It was the discovery of the placer mines in unappropriated land to which labor was free that raised the wages of cooks in San Francisco restaurants to $500 a month, and left ships to rot in the harbor without officers or crew until their owners would consent to pay rates that in any other part of the globe seemed fabulous.
…Henry George; Progress & Poverty Book V Chapter 2
George goes on to describe how gold mining was organized, and why it was the form of tenure rather than just the availability of gold that raised wages:
[I]t was by common consent declared that this gold-bearing land should remain common property, of which no one might take more than he could reasonably use, or hold for a longer time than he continued to use it. This perception of natural justice was acquiesced in by the General Government and the Courts, and while placer mining remained of importance, no attempt was made to overrule this reversion to primitive ideas. The title to the land remained in the government, and no individual could acquire more than a possessory claim. The miners in each district fixed the amount of ground an individual could take and the amount of work that must be done to constitute use. If this work were not done, any one could relocate the ground. Thus, no one was allowed to forestall or to lock up natural resources. Labor was acknowledged as the creator of wealth, was given a free field, and secured in its reward.
— Progress & Poverty, Book V, Chapter 2
And now I tripped over a 2002 paper (From Commons to Claims: Property Rights in the California Gold Rush by Andrea G McDowell) that provides a lot of detail and background supporting George’s assertion. A particular mining claim might be 100 to 900 square feet. A miner would work it for a few weeks, then expect to move on to another one. Thus the first miners to arrive had an incentive to avoid land monopoly, because they’d be looking for land again in a short while. “[The miners’] position can be summed up as a rejection of a fee-simple interest in mining claims on the grounds that this would result in the monopoly of the diggings by capitalists and the exclusion of individual miners from the chance to strike it rich.”
There’s a lot about how various mining districts managed their operations — certainly not all the same and often poorly documented, with a lot of the information coming from personal journals and correspondence rather than official sources.