Gold literally grows in trees

Money doesn’t grow on trees.

Or does it?

Well, not exactly, but scientists in Finland have discovered gold nanoparticles embedded in the needles of Norway spruce trees.

It’s kind of like those pre-decorated Christmas trees. These already have gold trim!

But don’t get too excited.

You can’t see the gold with the naked eye. As one article put it, “these particles are a few nanometers in size – barely big enough to make a nice bracelet for a bacterium.”

Even if you were able to harvest a large quantity of nanoparticles, they wouldn't weigh much. You're not going to get rich harvesting gold from trees.

However, understanding the process that moved gold into the tree needles could help miners find new gold deposits.

The process is called “biomineralization.” As the study explained, “Microbes and oxidation help metal ions travel from the soil, up through stems, and into leaves.”

In a nutshell, certain plant species can pull microscopic gold particles into their leaves or needles when their roots are buried in gold-rich soil. Scientists have known about biomineralization for quite a while. Eucalyptus trees in Australia have been known to contain trace gold. But the exact process that moves gold out of the ground into the plant remains unclear.

Finnish scientists discovered gold when they examined the needle samples from Norway spruce trees near the Kittilä gold mine. It ranks as the largest gold mine in Europe. The researchers pinpointed gold particles surrounded by bacterial microfilms embedded in needles from four trees.

“Our results suggest that bacteria and other microbes living inside plants may influence the accumulation of gold in trees,” first study author Dr. Kaisa Lehosmaa said.

“Our recent study provides preliminary evidence of how gold moves into plant shoots and how gold nanoparticles can form inside needles. In the soil, gold is present in a soluble, liquid form. Carried by water, the gold moves into the needles of spruce trees. The tree’s microbes can then precipitate this soluble gold back into solid, nanosized particles.”

Miners could use these gold-bearing trees to locate new gold deposits. In fact, a 2019 mineral exploration company used tree leaves to locate a 6-meter vein containing 3.4 grams of gold per ton in Australia.

Discovering gold in Norway spruce needles could facilitate gold exploration in the Arctic.

“This suggests that these specific spruce-associated bacteria can help transform soluble gold into solid particles inside the needles. This insight is useful, since screening for such bacteria in plant leaves may facilitate gold exploration,” Lehosmaa said.

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