While drilling, you may find potch (a good sign) or colour (the best sign). In Mintabie, fine quality opal can be found adjacent to worthless potch, therefore, any opal or potch drilled up is a very good sign that the ground is productive. Use any method for remembering which holes produced material (potch or opal). After your drilling program, you will be able to formulate the best option for recovering whatever pocket of opal you have drilled on.

By far, the best method of mining opal in Mintabie is the open cut method. The reason for this is that the bulldozer cut exposes every cubic metre of ground in the entire area of the cut. This means that all of the opal that exists in the area of the open cut will be located in the process.

In comparison, underground mining exposes only the opal bearing level being worked at the time, and because pillars must be left when working underground, it is possible that the best opal in the claim may be left behind.

Underground mining still has its place, however. In cases where the opal is drilled near an open cut or existing underground workings, the opal can be recovered easily and quickly, without the need to contract a bulldozer.