The history and provenance of diamond mining is the fascinating stuff of which movies are made. And they were. Blood Diamonds, (2006) starring Leonardo DiCaprio, portrays diamond mines in war zones which were sold to finance conflicts and to profit its warlords.
But today, thanks to the Kimberley Process Certification Scheme, a highly regulated system of certifying diamonds has put the kibosh on such illicit practices. “KP members are responsible for stemming 99.8% of the global production of conflict diamonds,” reports the Kimberley Process on its website.
Still, we are enthralled with the mystery and romance surrounding the hunt for diamonds. They are always found in some hard to access region of the world. The geology surrounding their locales is very particular. In brief, diamonds are found in areas where ancient volcanic activity once occurred, leaving the tell-tale kimberlite – volcanic pipes, or lamproite – its diamond-bearing rocks in their wake. It all sounds very foreign and exotic. And it is.
Where are diamonds found?
Irrespective of the region, diamonds are harvested from areas with kimberlitic pipes or for those having washed down the pike, in alluvial deposits. Kimberlite rocks occur in ancient volcanic pipes, and are considered to be diamonds’ main hosts. These rocks are eventually transported over rivers, streams and waterfalls far away to their eventual deposits. Diamond crystals in kimberlite can travel great distances and eventually end up in the water at far flung alluvial deposits.
Diamonds are found in about 35 countries today. While Botswana, South Africa, and Russia are the main producers of gem quality goods, Australia is the major producer of industrial grade diamonds. To some lesser degree, they are also found in Russia, Canada, India, China, Siberia, Brazil, and the United States. What? The good ol’ US of A? That’s not exotic at all.
Diamonds in the USA
If you follow various newsy outlets, you’ll occasionally encounter a fun clip about someone finding a diamond in the Crater of Diamonds State Park in Arkansas. There are other US diamond regions well off the radar, located in Colorado and Wyoming. But how on earth did any of this happen?
Turns out, the geology responsible for producing diamonds, like those iconic kimberlite pipes can and do occur in the USA. Some time back, a kimberlitic-rich area at the Colorado Wyoming border was open to the public for tourist mining. While it closed over two decades ago, there are rumblings that they will reopen access to the currently defunct mines. They must know something.
The story of diamonds found at the Crater of Diamonds State Park harkens to more than 3 billion years ago in the earth’s mantle. There, diamonds formed much the same as they did in South Africa or India before that. Under conditions of tremendous pressure and extremely high temperatures about 100 miles or so below the earth’s surface, diamonds crystallized from carbon.
Too Much Info?
Some 300 – 250 million years ago, the terrain of what we now call South America collided with the southern portion of our present-day North America. About 100 million years back, instability in the earth’s mantle produced a ferocious movement of gas and rock to the earth’s surface. This volcanic vent, which geologists call “Prairie Creek”, rose rapidly through the upper mantle and crust. It carried with it mantle fragments, rocks and minerals, until it approached near enough to the surface to explode, thus releasing pent-up gases. The result was an 83-acre funnel-shaped crater with sides sloping inward at about a 45° angle. Much of that explosive airborne material fell back into the vent. Fortunately, diamonds were preserved in this eruptive material.
Crater of Diamonds Unique Features
Exciting news for rock hounds is that geologists gauge that only about 160 feet of its original vent has been eroded away. This means a concentration of its minerals, including diamonds, are in the present-day soil. At the Crater of Diamonds State Park, tourists usually pick up diamonds from the loose soil that was weathered in its unstable mantle rock.
This home grown mine is publicly owned by the state of Arkansas today operating as a park. Visitors can scour for diamonds and keep what they find. This US mine has produced over 75,000 diamonds since records have been kept.
First a Farm
Long before it became a diamond hunting destination, it was just a farm. In 1906, the first diamonds were accidentally discovered by farmer John Huddleston, a who owned the land decades before it was converted into a State Park in 1972.
Today, some tourists are drawn to this spot for the thrill of the hunt for a diamond. And they may find one. On Labor Day in 2020, Arkansas native Kevin Kinard found a large, brown gemmy diamond weighing 9.07 carats. It happens to be the 2nd largest diamond ever found there. This year, in May 2021, 26-year-old Christian Liden, of Poulsbo, Wash., claimed he wanted to find a raw diamond to make his own engagement ring. And he did! Liden came upon a 2.20 carat yellow diamond.
As happy as we are for the successful diamond hunters, we also know people go to the park for completely different reasons. Those are rockhounds with a passion for geology. They are awed by the region’s lamproite and volcanic pipes that created this site here on US soil. In a way, that makes Arkansas exotic too.