The Department of Mineral Resources, a NSW Government body, oversees the orderly running of opal mining in the Lightning Ridge area. A part of the Department's job is to see that the fields are kept in a safe and clean manner, and ensure that the claims are rehabilitated.

With underground mining this is a reasonably simple operation for the miner. A $100 bond is imposed for each claim to ensure that the shafts are filled in at the completion of mining. With open cut mining a much larger bond is required, depending on the amount of claims and the depth to be mined. Bonds of up to $30 000 per claim (2500 m2) are being charged to open cut the newer fields. This tends is to slow down the smaller miner from open cutting. This cost, on top of the cost of the machinery, trucks, agitators etc., as well as the Mining Purpose Lease, puts open cut mining costs in the $700 000 region.

Here at Opal Shed Mining Co we do most of our operations by the open cut method. These three photos show some of the equipment that we use to win the opal from this hard rocky land. The mines in the Lightning Ridge mining area are mostly covered by a layer of sandstone that varies in thickness from 150mm (6 inches) to 10 metres (35 feet). The sandstone sits on top of the opal level. All the sandstone and the dirt above sandstone have to be removed, and stockpiled in separate heaps for later rehabilation.

Once the overburden has been removed it is then possible to remove the opal dirt layer. This layer is then screened through a trommel to remove the sandstone rocks and the very fine opal dirt. The opal dirt is then transported back to our washing plant, situated at Nine Mile Field.

Our washing plant consists of three agitators (concrete agitators that have been modified to run 24 hours a day, seven days a week), that wash the opal dirt (a type of clay) from the opal. The plant has the capability to wash 200 m3 daily. The daily through-put is entirely dependant on the type of opal dirt being washed.

The first two photographs here show the opal dirt being tipped into conveyors that loads the agitators, and then the dirt is mixed with just enough water to make a slurry, which is seen here dropping from the agitator.

Once the agitator has enough retained material to 'tail out', the sorting bin is filled. This is shown in the last photograph here, as Gordon and David do a rough sort, before the material is transported back to our Gold Coast premises for further sorting, cutting and polishing, and display in our showroom.