One technique uses a dry blower - pressurized air is blown through dirt that is loaded into a hoppah using a front loader and the lighter portions of the soil are blown away and then the heavier parts are run through vibrating trays to separate the gold flakes and nuggets from the regular dirt. It's the equivalent of sluice mining in a place with no water.
The machines are gigantic and prone to breakdown way out in the bush, hundreds of miles from any repair shop. The crews carry tools and spare parts but some bush repairs are beyond their means. One major part of the Goldzilla dry blower suffered from multiple fractures due to metal fatigue and had to take the long trip to town to be welded.
My personal favorite mining method shown is miners walking around using a metal detector and finding nuggets, sometimes an ounce or two in weight, either right on or just below the surface of the soil. That's good stuff right there. Of course they find other odd bits of metal, but that is a miner's life in a nutshell.
But how this series connects to my life, besides the heat (it's 50 over there, pronounced 'fiddee' and that, apparently is hot) is the fact that once again I was using a machine and it broke. The front guide wheel on the mower deck on my John Deere lawn tractor snapped off and went into the rotating blades. There was a brief moment of excitement but soon everything was shut down and damage assessment and then repair commenced. I borrowed my neighbor's small hydraulic lift and once the tractor was in the air I was able to deftly remove the mower deck. Once the deck was inverted and clamped to my sawhorses I was able to use a sledge hammer to pound the front part of the deck clear of the path of the blades. I tried welding the wheel bracket back on but I have poor welding-fu and a weak wire welder - this is a job for a stick welder, so this morning I hauled the deck to the local tractor repair shop. I have been taking machines to this shop since 2000 and while they do good work they are profoundly slow. Molasses thinks they are slow. The upside is that now I have an excuse to ignore my lawn and work on other tasks - my mower is down for the count.
I have always been drawn to gold mining but have never so much as panned a bit of it - my brother did 60 years ago on the aptly named Goldmine Road near where we lived. He got over five cents of gold flakes. I think he gave up too easily.