Our Mine belongs to the Boulder Opalfield known as Koroit and is situated approximately 80kms north-west of the town of Cunnamulla in south-west Queensland. It produces a beautiful Boulder Opal Matrix where the Opal is found in the fine cracks, crevices and holes in the ironstone.
The Opal can sometimes form in small cavities or kernels towards the centre of the boulder or in the outer layers or ‘skins’ of the boulder. But the unique mix of the brown ironstone host-rock and Opal can produce the most fascinating and amazing patterning that just dazzles the eye. Our Mining Lease is approximately 23 hectares (50 acres) so there is a lot of ground to explore.
We mine by the open-cut method using a large excavator to break open the cap-rock and dig down to the opal-bearing levels These levels can be fairly shallow at 3metres or as deep as 20metres depending upon the movement and changes in the ground over millions of years. A level is a group or layer of boulders which have become filled with silica (Opal) as these vast areas of inland sea gradually dried out. We then try to assess today where these levels of boulders lie and unearth them in the hope that the boulders will contain the precious Opal. Here are some of the signs we are looking for fault lines or traces of boulders already exposed in old diggings. We’ll keep you informed.