Task 1:
Describe how and why people use the region for mining
Coober Pedy, or White Man’s Hole, is located in the north of Southern Australia, 750km north of Adelaide. It is world renowned for its abundance of opals and opal mines. This is why it is called “the opal capital of the world”. The opal fields cover an area of approximately 5,000 km2, and produce more opals than any other place in the world.
Opal was first discovered in Coober Pedy in 1915, when Jim Hutchinson and his son, William, stumbled across pieces of opal during an unsuccessful trip searching for gold. During the 1960’s, the mining industry in Coober Pedy took off and expanded dramatically. Migrants from Europe had travelled to the desolate town in search of fortune.
Opal is a form of silica. Its chemical makeup is similar to that of quartz, however it contains water within the mineral structure. Usually, opal consists of 6-10% water. The silica spheres diffracting white light create the colour in precious opals.
All precious opal that is mined in Southern Australia comes from rocks that were affected by weathering millions of years ago. As water moves down below the surface of the Earth, it picks up silica from sandstone. This silica-rich solution is then carried into rock cavities, caused by the decomposition of fossils or natural faults. When the water has evaporated, a silica deposit remains. After this cycle has been repeated over and over for very long periods, opal is formed, usually 20m-25m underneath the ground.
Unlike many types of mineral mining, opal mining only requires one worker. The traditional and least expensive method is sink shaft mining. A shovel and pick is used to dig a hole straight down into the ground until material is found that looks promising, often called “opal dirt”. Explosives are then used to dig further into the ground, parallel to the surface, at the depth that this opal dirt was found in hopes of discovering the mineral. This older method has been almost replaced by using Calweld drills, which are used to excavate holes about 1m in diameter. These drills work very efficiently and can reach depths of up to 30m below ground level. Truck-mounted blowers are used for bringing the waste material or mullock to the surface, similar to a vacuum cleaner.
Australia was covered in a shallow sea, known as the Eromanga Sea about 110 million years ago. Over time the floodwaters receded from the land, leaving behind what we now call opal. 95% of opals are mined in Australia.
There are some laws and regulations regarding opal mining in Australia. All miners require a Mining Permit. This allows them to peg a claim either 50m x 50m or 50m x 100m, depending on the situation, to mine for opal. Additionally, once a mine has been completed, it must be filled in again or covered with sheet metal to help prevent any danger and to ensure that the empty mine shafts do not pose a threat to people or wildlife.
Opal was first discovered in Coober Pedy in 1915, when Jim Hutchinson and his son, William, stumbled across pieces of opal during an unsuccessful trip searching for gold. During the 1960’s, the mining industry in Coober Pedy took off and expanded dramatically. Migrants from Europe had travelled to the desolate town in search of fortune.
Opal is a form of silica. Its chemical makeup is similar to that of quartz, however it contains water within the mineral structure. Usually, opal consists of 6-10% water. The silica spheres diffracting white light create the colour in precious opals.
All precious opal that is mined in Southern Australia comes from rocks that were affected by weathering millions of years ago. As water moves down below the surface of the Earth, it picks up silica from sandstone. This silica-rich solution is then carried into rock cavities, caused by the decomposition of fossils or natural faults. When the water has evaporated, a silica deposit remains. After this cycle has been repeated over and over for very long periods, opal is formed, usually 20m-25m underneath the ground.
Unlike many types of mineral mining, opal mining only requires one worker. The traditional and least expensive method is sink shaft mining. A shovel and pick is used to dig a hole straight down into the ground until material is found that looks promising, often called “opal dirt”. Explosives are then used to dig further into the ground, parallel to the surface, at the depth that this opal dirt was found in hopes of discovering the mineral. This older method has been almost replaced by using Calweld drills, which are used to excavate holes about 1m in diameter. These drills work very efficiently and can reach depths of up to 30m below ground level. Truck-mounted blowers are used for bringing the waste material or mullock to the surface, similar to a vacuum cleaner.
Australia was covered in a shallow sea, known as the Eromanga Sea about 110 million years ago. Over time the floodwaters receded from the land, leaving behind what we now call opal. 95% of opals are mined in Australia.
There are some laws and regulations regarding opal mining in Australia. All miners require a Mining Permit. This allows them to peg a claim either 50m x 50m or 50m x 100m, depending on the situation, to mine for opal. Additionally, once a mine has been completed, it must be filled in again or covered with sheet metal to help prevent any danger and to ensure that the empty mine shafts do not pose a threat to people or wildlife.