Lightning Ridge is located roughly 500 miles Northwest of Sydney deep in the Australian bush. It is a small town that thrives on mining and tourism amidst extreme heat, drought, and the occasional flood. Over the last century it has been a place of fortune and fame for some, and disillusion and toil for others.
The fields extend for 900 square miles around the town and although the mining area is vast, the pockets of opal within the fields in this area are very rare and occur sporadically between 15 and 90 feet below the surface, making the search for the elusive gemstone very difficult. Some miners may go for a decade or more prospecting and digging barely covering costs.
When commercial production commenced in 1904 until the mid 1950’s, mining was done painstakingly through manual labour with a shovel, pick, and windlass. The miner would pick an area he thought might be rich and sink a shaft by shovel through the initial layer of clay and sandstone, called shincracker locally, until the opal level was reached. This process might take up to three weeks, and if the shaft they sunk didn’t provide any promise then the task might be abandoned for another area found. However, if the area was promising then they would put in a drive horizontally looking for nodules, or ‘nobby’s’, of rough opal using a candlelight and pick, with the excess dirt being carried up the shaft using a hand wound windlass.
The 9-inch auger drill at work.
Today modern machinery has eased the burden of a still painstaking process through the use of a 9-inch auger drill to prospect. When searching for a new location the miner will look for indicators in the surrounding geology that might give them a clue as to what lays underground, whether it be tree formation, the way the land runs, or other factors. There are no sure fire indicators and it is all an educated guess but a hunch is better than nothing.
Once an area is decided upon and a 28 day prospecting license is obtained, the miner will use a 9-inch auger to drill underground. The drill is shaped in a way that it brings pieces of the earth underground to the surface, giving indicators of what lies underneath. If there is colour then work will commence. The process is still very painstaking because a patch of rough can be missed by inches amidst tens of miles of mineable bush land.
Promising results from prospecting with the 9-inch drill showing nice colour in the rough chips brought to the surface.
If the signs are positive then a 3 foot wide shaft will be sunk using a Caldwell drill down to the level that produced color between 15 and 90 feet underground. Once the level is reached tunnels are dug out to create what are called drives. The miner will use a jackhammer or air compression drill to start the drive.
Once the base of the shaft has been opened out and a main room is created, referred to as the ballroom, then a miner may continue to make drives in directions through the opal level, shoveling the dirt into a bucket attached to an automatic hoist which carries the bucket up the shaft via a cable. The level itself is a sort of damp clay dirt, however it varies from field to field.
Alternatively the miner may introduce a digger once enough room has been created in the ballroom. This uses a hydraulic arm that pulls dirt off the face of the wall and feeds into a blower, almost a giant vacuum. The blower sucks the dirt up above ground into a holder, known as a hopper, on ground level, which then traps the dirt until it has enough volume and is released into the truck.
Using a digger and a blower is more costly to run and runs more risk at damaging the rough opal then a handheld jackhammer, but it allows you to move much more dirt each day.
Tunneling dangerous work with a constant risk of falls that can result in injury and death. At one time opal mining was the most dangerous form of mining in Australia.
It is also painstaking. These miners had been working this claim for six years and had gone 9 months without finding any payable material.
Across the entire right face of the drive in the photo (far left) only one nodule of rough opal was found.
Open cut mining is also performed at Lightning Ridge. Due to the scarcity of gem quality opal throughout the fields, the difficulty in negotiating leases with the government, and the high costs of excavating millions of cubic tons of earth using heavy machinery, it is usually reserved for areas where rich claims were found using tunneling methods, and it has been decided that the entire patch wasn’t found and thus the whole area should be excavated.
The cost of investment is high, as are both the risks and the possible rewards.
The entire overburden must be removed and dumped legally and a bond is imposed by the department of mineral resources.
The land is then rehabilitated in accordance with government regulations.
Once the dirt is above ground it is loaded onto trucks and then carted to the processing area, called the puddling damn, where it is put through a modified cement mixer, called an agitator, for up to 2 days to wash away the clay and dirt and leave only the hard rock left. What is left is called the tailings and the miner will then sort through these tailings to hopefully find rough opal.
The rough opal goes through an arduous process from being dug out with heavy machinery, sucked up at high velocity to the surface and dumped into trucks, to being churned for extended periods of time in cement mixers.
Tailings from the puddling dam
Agitator and Small Front End Loader
A faced up piece of rough.
The rough nodules are then gathered. Rough fresh out of the ground may have little or no colour showing so the excess dirt surrounding the opal will be removed, this is called the rub.
The cutter will then determine the best way to cut the stone. The goal is to obtain as much value as possible, facing the best color, the highest possible cabochon, and the most saleable shape. It requires the ability to almost see within the rough and imagine what can be obtained.
The stone is roughed down on a grinding wheel of course diamond grit until the colour is faced up, and then the shape is determined.
The stone is then moved from finer to finer diamond grit on the grinding wheels until finally it is polished and the final gemstone is produced.
On the Grinding Wheel
The final gemstone is priced and then moved overseas to our distribution points where we then distribute it to wholesale dealers, manufacturers, jewelers, and retailers, and eventually the final consumer.
One of our finest gems ever resting in the freezer after being cut. This is done sometimes to help remove the dopping wax that has been stuck to the stone.
The 49.27ct final result.