Argyle diamond mine facts for kids
The open pit of the Argyle diamond mine. A large mining truck is visible on the road for scale.
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| Location | |
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 Argyle Diamond Mine
Location in Australia
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| Location | Lake Argyle |
| State | Western Australia |
| Country | Australia |
| Coordinates | 16°42′44″S 128°23′51″E / 16.71222°S 128.39750°E |
| Production | |
| Products | Diamonds |
| History | |
| Opened | 1985 |
| Closed | 2020 |
| Owner | |
| Company | Rio Tinto Group |
| Website | www.argylediamonds.com.au |
The Argyle Diamond Mine was a famous diamond mine in a far-off part of Western Australia. For a while, it was the biggest diamond mine in the world by how many diamonds it dug up. But most of these diamonds weren't the super shiny, perfect ones you see in jewelry.
It was super special because it was almost the only place in the world to find rare pink and red diamonds. It also had lots of other naturally colored diamonds, like champagne, cognac, and even some rare blue ones!
The mine stopped working in November 2020, after 37 years. During that time, it produced over 865 million carats of rough diamonds. The company that ran the mine, Rio Tinto, is now cleaning up the site.
The Argyle mine was also special because it was the first successful diamond mine to dig up diamonds from a type of rock called lamproite. Most other diamond mines find diamonds in a different rock called kimberlite. The Argyle mine was owned by the Rio Tinto Group, a big mining company.
Contents
What Was the Argyle Diamond Mine Like?
The mine area was about 50 football fields big. It stretched for about 1600 meters long and between 150 to 600 meters wide.
How Did They Mine Diamonds?
At first, Argyle used an open-pit method. This is like digging a giant hole in the ground. The hole got about 600 meters deep! The open pit closed in 2010. After that, they started digging for diamonds underground in 2013.
Where Was the Mine Located?
The Argyle diamond mine was in the Kimberley area of Western Australia. It was near Lake Argyle, about 550 kilometers southwest of Darwin.
Because the mine was so far from towns, a whole living camp was built right there. Most of the 520 workers traveled from Perth, which is over 2000 kilometers away. They worked for two weeks, then went home for two weeks. The mine also hired many local Indigenous people.
History of the Argyle Diamond Mine
People knew about small amounts of diamonds in Australia since the late 1800s. But they couldn't find the main source of these diamonds.
How Was the Mine Discovered?
In 1969, some diamonds were found in another part of Western Australia. This led mining companies to start a big search. In 1979, a woman named Maureen Muggeridge found diamond samples in a creek that flowed into Lake Argyle. She followed the creek upstream and soon found the main source of the diamonds. This was the Argyle pipe, discovered on October 2, 1979.
Building the Mine
For the next three years, experts checked if it would be worth digging for diamonds there. In 1983, they decided to start mining. They began digging up diamonds from the creek beds right away. The big open-pit mine took 18 months to build and cost about A$450 million. The mine officially opened in December 1985.
How Diamonds Formed at Argyle
The Argyle mine was special because it was the first successful diamond mine not found in a kimberlite pipe. The main diamond source was a volcanic pipe called "AK-1."
Diamonds were found inside this volcanic pipe. The diamonds found here are very old, about 1.58 billion years old. The volcano that made the pipe erupted about 1.1 to 1.2 billion years ago. This means the diamonds formed over a relatively short time. This might explain why Argyle diamonds are usually small and have unique features.
Besides the main pipe, some nearby streams washed away parts of the pipe over time. This created other places where diamonds could be found, and these were also mined.
Diamond Production at Argyle
Argyle was the fourth-largest diamond mine in the world by how much it produced. It dug up about 8 million carats of diamonds each year. Production was highest in 1994, when it produced 42 million carats! The open-pit mine alone produced over 750 million carats of rough diamonds.
Types of Diamonds Found
Most of the good quality diamonds from Argyle were brown diamonds. These were sometimes hard to sell. But Rio Tinto had a long-term plan to market them as "champagne" and "cognac" colored diamonds, which helped them sell.
On the other hand, the mine had no trouble selling its pink, purple, and red diamonds. These colors are very rare and in high demand, so they sold for very high prices. The pink diamonds were cut and polished by a special team in Perth and sold to people all over the world.
The mine had special machines to process the ore and sort the diamonds. After the diamonds were cleaned, they were sorted and sent to Perth for more sorting and sale. Many of the smaller diamonds were sent to India to be cut. This was because it was cheaper to cut small diamonds there.
What Made Argyle Diamonds Special?
The diamonds from the Argyle mine were generally not as high quality as diamonds from other mines. Only about 5% of the diamonds found were considered "gem quality." This is lower than the worldwide average of 20%.
Most Argyle diamonds (80%) were brown. Then came yellow (16%), white (2%), grey (2%), and less than 1% were pink and green. Even though they produced a small amount, the Argyle mine was the only reliable source for 90 to 95% of all pink and red diamonds in the world.
The Annual Diamond Tender
Every year from 1984 to 2021, a very small collection of the best pink diamonds was sold at a special event. This event was called the Argyle Pink Diamond Tender, and only a few people were invited. For every million carats of rough pink diamonds found, only about one carat of polished pink diamond was offered for sale at this tender.
In 2009, Argyle also held its first sale for rare blue diamonds. This collection, called "Once in a Blue Moon," included blue and violet diamonds found over several years.
The tenders in 2016 and 2020 set new records for sales. The final tender in 2021, after the mine closed, also had record-breaking results.
Why Was Argyle Economically Possible?
The Argyle diamond mine was profitable because it had huge amounts of ore and a high concentration of diamonds. Even though the diamonds themselves weren't worth as much per carat as those from other mines, the sheer number of diamonds made it worthwhile.
For example, Argyle diamonds were valued at about US$7 per carat. Diamonds from other mines, like Diavik or Ekati in Canada, were worth much more (US$70 to US$170 per carat). But Argyle had two to four times more diamonds in its rock. This meant that even with lower-value diamonds, it was still worth digging them up. This is because the cost of mining mostly depends on how much rock you dig, not how many diamonds you find.
Moving to Underground Mining
In 2005, Rio Tinto decided to expand the mine by moving from an open pit to an underground mine. This plan was delayed, but in 2010, Rio Tinto announced new plans to dig an underground mine beneath the existing pit. This would increase the amount of ore dug up each year.
The underground mine was finished by 2013. It used the newest mining technology. However, digging deeper underground was more expensive. Eventually, the costs of mining started to be more than the value of the diamonds they found.
Mine Closure
In 2018, it was announced that the mine was no longer making enough money to keep going. So, the mine stopped producing diamonds on November 3, 2020. After that, the remaining ore was processed for six more months.
Now, there will be a ten-year project to restore the land. This will be done with the help of the traditional owners of the land. Sales of the last diamonds from the mine continued into 2022.
See also
- Argyle Pink Jubilee
- Argyle Airport
- Argyle Library Egg
Images for kids
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The open pit of the Argyle diamond mine. A large mining truck is visible on the road for scale.
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An uncut diamond crystal from the Argyle mine, 4.27 carats
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The Argyle Diamonds logo
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A large brown Argyle diamond, 3.6 carats
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Aerial view of the open pit in 2007
