Mining opal today still has all the aspects of a Wild West town from 1800s United States. Most of the Australian opal is found in the country’s remote deserts, which has a “blistering, almost unliveable climate.” Indeed, many opal miners dig their living quarters underground, in an attempt to stay cool.

Lightning Ridge, on the other hand, is significantly cooler, and there’;s enough moisture to support tree growth (albeit, scrub trees).

However, there’s till not a lot of water, so what the miners do is form “wash cooperatives.” Since it’s easier to find opal when its wet, all the dirt and gravel dug out of a mine is driven to one od many dam sites. There, the material is dumped into an agitator. The dirt is tumbled around for 4 to 5 hours, sprayrf with water, so that most of the gravel pours out of the sides of the agitator. The rest of the material slides down into an area where the miners look it over, inspecting each piece by hand.

The residue, the grit and gravel, is dumped into “mullock heaps” near the top of the dam.