When Diamonds are a Plant’s Best Friend

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Rough diamonds.

Diamond prospectors now have a new research tool: scientist Stephen Haggerty of Florida International University recently discovered a plant that seems to be able to reveal the presence of diamonds in the soil.

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Chandelier tree (Pandanus candelabrum). Photo: Marco Schmidt, Wikimedia Commons

The chandelier tree (Pandanus candelabrum) seems to grow only on kimberlite “diatremes” (outcrops). Kimberlite is an exceptionally mineral-rich rock, so rich in fact that it is toxic to many plants. The chandelier tree, however, appears to have adapted to kimberlite soils and only grows in them, at least in the wild. What’s so interesting to prospectors is that kimberlite diatremes are also where diamonds are found.

In the dense, swampy jungles of Africa, geologists have a hard time finding kimberlite diatremes. They’re very sporadic, appearing here and there, and may be only a few meters in diameter. Searching on the ground for sites potentially rich in diamonds is therefore extremely difficult. It’s therefore very helpful to know that a specific tree can help find these outcrops quite easily… and that the tree in question can be readily spotted from a helicopter.

Not in Your Backyard

Before you go off in search of chandelier trees in your backyard, however, you need to know that this indicator plant only grows in Africa and even there, only in warm, moist areas near the heart of the continent. In other words, only in jungles. Moreover, even if the chandelier tree definitely indicates the presence of kimberlite (since it never grows in other soil type), it’s important to understand that all kimberlite diatremes do not contain diamonds, or at least not enough high-quality diamonds to be worth harvesting. Only about one kimberlite diatreme in 60 is rich enough in quality diamonds to deserve consideration for mining.

Other Indicator Plants

Amorpha canescens

The appropriately named lead plant (Amorpha canescens) grows only in soils rich in lead.

However, the chandelier tree is not the only “indicator plant” (a plant that indicates the presence of specific minerals in the soil). In North America, for example, the lead plant (Amorpha canescens) is only found on soils that contain lead, while you’ll never see Patterson’s milkvetch (Astragalus pattersonii) unless the soil is rich in uranium. And in Europe, if you see the yellow calamine violet (Viola calaminaria), you can be sure the soil is contains lots of zinc. And there are dozens of other examples.

It would be interesting to study the flora associated with the presence of kimberlite in northern North America, where there are several diamond mines, to see if a more cold-hardy indicator plant couldn’t be found. Maybe then you might find a diamond deposit in your own backyard!20161016b

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