Reading. Interesting fact about eucalyptus

Leaves of eucalyptus may contain gold even if they are not golden. 

Money does not grow on trees. But gold does. Not everywhere, not on every tree, but it does.

People often talk about golden leaves in autumn, but this is a metaphor. This text is about trees, leaves of which really accumulate gold. And not only leaves, but also bark.
Australian scientists have been examining eucalyptus trees in Southern and Western Australia and have discovered tiny particles of gold contained within leaves and bark of these trees. But how did those particles get there? It appeared that trees sucked them out of the soil together with water. Deeply underground gold gets dissolved in water and gets sucked in by trees. Then it accumulates as small particles. This does not make any good to the tree; it sheds its leaves, which accumulated too much gold. But what is too much for the tree is not much for us. You would need to extract all gold from leaves and bark of 500-600 trees to make just one small wedding ring. This is not practical because the cost of such extraction would exceed prices for gold mined in traditional ways.
But still this discovery can be very useful for the gold mining industry. A considerable part of expenses of this industry (and thus, the cost of gold) is related to finding new gold deposits. Exploration of deposits requires drilling many wells and digging many small and deep pits on very large territories. This process is very expensive and causes a lot of collateral damage to the environment. Instead of this, it is enough to analyze leaves of eucalyptuses in the same area. They indicate presence of gold up to 30 meters deep in the earth.
For these findings scientists used the Australian synchrotron, a particle accelerator, in which collision of particles is used for producing very powerful X-ray radiation. This radiation was directed to the leaves. Each atom in a leaf deflects the X-rays in its own particular way. Atoms of gold do this in a very distinct way; therefore, presence even of a single atom of gold in a leaf can be accurately detected and the total quantity of gold can be accurately measured. These measurements help to conclude if the gold deposit in a particular place is worth mining or not.
This text is based on the information presented in the "Dr. Karl and the Naked Scientist" BBC radio program. October, 2013.