The Plant That Only Grows Around Diamonds

“Perhaps time’s definition of coal is the diamond.” —Khalil Gibran

In A Nutshell

Thanks to De Beers, diamonds are in constant high demand all over the world. Finding new diamond-rich locations can be a challenge, but the presence of a single plant, called Pandanus candelabrum, can indicate a likelihood of diamonds below. The palm-like plant only grows around kimberlite pipes, volcanic pipes that are millions of years old. The pressure inside the kimberlite pipes makes them ideal locations for the formation of diamonds, and finding them has just gotten easier.

The Whole Bushel

There’s a certain sort of exotic mythos that’s grown up around diamond mining and the diamond, and a lot of that is thanks to the marketing campaigns of De Beers. They made diamonds the stone to have, which has turned diamond mining a rather cutthroat operation. Science now says there’s a weird little trick to finding diamond-rich soils.

Just look for a plant called Pandanus candelabrum.

It’s easy to find, too, growing up to 10 meters (33 ft) tall and looking a bit like a spiny palm tree. It grows throughout Africa, but more importantly, it only thrives in areas around kimberlite pipes.

Kimberlite pipes are rare tubes of rock and minerals formed by magma as it cools in a reaction that starts deep inside the Earth. The pipes form as volcanic activity pushes molten rock toward the surface. The molten rock cools along the way, forming the pipes. Most of them are pretty ancient, with some dated to as far back as 1.2 billion years ago. More common are slightly younger ones—between 70 and 150 million years old—and they’re almost all found in areas where the Earth’s surface has remained unchanged since their formation.

As minerals and rocks are pushed upward through the pipes, the narrowing chambers increase pressure, which is exactly what a diamond needs. We’ve long known that the presence of kimberlite pipes will likely yield diamonds, and now botanists have discovered a correlation with the plant growth around the pipes.

Botanists aren’t quite sure if P. candelabrum only grows around the kimberlite pipes, but it’s the only place it’s been found so far. It seems to be able to survive only in these soils, which are incredibly high in minerals like potassium, phosphorus, and magnesium.

All in all, kimberlite pipes are rare, and rarer still are those that contain enough diamonds to make a mining operation worthwhile. Only about 6,000 pipes have been discovered, and only a small fraction have been deemed worthy of a full-scale mining operation. Part of the problem in finding them is that they’re often in isolated, heavily forested areas where exploration is still difficult. But the discovery of the massive palms as an indicator species might make finding more of them a whole lot easier.

The idea of using plants as indicators to find precious stones and minerals is one that has something of a precedent in other parts of the world.

The Haumaniastrum katangense is more commonly known as the copper flower, and its unique physiology has allowed it to carve out a niche in its environment. Where there are high deposits of copper, there are also extreme soil conditions that many plants can’t survive. This one can, though, and it’s found throughout the African Katangan Copper Belt and marks high concentrations of copper. Studies of the plants show that some members of the family have adapted so well to the presence of usually toxic copper in the soils that they display enhanced chlorophyll activity when the soil has a sufficiently high copper concentration.

Show Me The Proof

Featured photo credit: Marco Schmidt
Science: Rare African plant signals diamonds beneath the soil
ScienceDaily: How diamond-bearing kimberlites reach the surface of Earth: Acidification provides the thrust
International Gem Society: Are diamonds really rare? Myths and misconceptions about diamonds
Environmental and Experimental Botany: Differences in copper accumulation and copper stress between eight populations of Haumaniastrum katangense