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Last updated:  June 2006

Aussie Sapphire is a family owned business operating a diverse range of enterprises including cropping, grazing and sapphire mining. While sapphires have been mined on our farm for many years, we became directly involved in running a commercial mine in 1998.  This was an interesting process as we had to learn about many other aspects of the sapphire mining business – being a sapphire miner was not “just digging them up”.

The first part of this article outlines the process of commercial mining.  Subsequent sections deal with processing of the mined sapphire (separating, sorting/grading, cutting and marketing.

Where to dig?

The first step of the process is deciding where to start digging!  This usually requires a mixture of experience, the use of test holes using an excavator, core test drills, prior knowledge on where the old ground is and inspired guesswork.  I also like to add in a bit of divining using 2 bits of old fencing wire and a big chunk of corundum – sounds like moonshine but it works.

Following the wash

Once you have found a promising spot to dig, the first step is to strip off the overburden and start the cut. Click here for a short video clip of an excavator at work.  To understand the process, let’s explain the soil layers. On top of course is the top soil, in our case around 200 mm, then the subsoil which goes down to the wash layer.  Below the subsoil is the all important wash layer - in certain areas, this layer may be very deep but we are lucky with relatively shallow wash (1 – 4 m).  I am often asked what does wash look like. In our case there is no simple explanation. Our wash varies considerably, it is unusual for us to dig more than a few metres of the same kind of wash; depth and thickness also changes constantly. Our wash layer is also usually very clayey with large lumps of mud mixed with the sapphire bearing gravels. Normally, good wash has an amount of coloured rocks contained in it, along with considerable amounts of ironstone.

Picking the variations in wash requires the excavator operator to keep on his toes as money can be lost with an operator who cannot recognise the wash layer properly.  As the excavator works along the cut following the wash, it is progressively filled back in with processed gravel returning from the mining plant and subsoil which has been set aside.  The final step is to replace the top soil which is spread over the layer of subsoil that has been levelled and rolled with the excavator.  Restored areas are returned to agricultural production.

The next phase of the process involves processing the truckloads of wash through the mining plant.  Click here to go to the next page to learn more about this.