In Queensland most mining is done with bulldozers and excavators. They push the top soil away with the bulldozers and dig for the opals with the excavators. They are looking for large ironstone boulders, which will broken up. Hence the name Boulder Opals.
In most other areas a three foot hole is drilled and a ladder is put down. Then tunnels is made with jackhammers or hydraulic diggers and the dirt is brought up with a hoist or a blower, witch works as a huge vacuum cleaner.
In Lightning Ridge the dirt is washed in old cement mixers to separate the opals from the dirt.