When the scientist Alan Baker analyzed the appearance of a plant discovered in the Philippine jungle, the sap it exuded had a jade green glow.
The shrub was a recently discovered species, the phyllanthus Balgooyi, a rare amount of vegetation that naturally absorbs significant amounts of metal components from the soil.
The fluorescent sap turned out to be made up of as much as 9% nickel.
The hyperaccumulators
An undoubtedly welcome discovery. Not a shock, however: as Professor Baker's analysis of so-called "hyperaccumulators" had already discovered plant species that appear to absorb everything from cobalt to zinc, even gold.
'This is vegetation that can collect components from the soil in much greater quantities than normal vegetation,' says Professor Baker.
Of the 300.000 plant species recognized on Earth, only about 700 have hyperaccumulation properties.
Plants that exude metal
The blue latex of the rare pycnandra acuminata present in New Caledonia contains 25% nickel.
Scientists are trying to find out whether cultivating this vegetation may or may not be an environmentally substitute for mining. Is there an industrial potential for agromining? Can metal be "cultivated" rather than extracted?
College of Queensland plant specialist Dr. Antony van der Ent recognizes this practice also with the term "fitomining".
Macadamias, baby
In his chemical evaluation laboratory on the outskirts of Brisbane he is currently carrying out evaluations on what is today the best-known hyperaccumulator of all: the tree of Macadamia.
It is widespread in Southeast Asia, New Caledonia, Cuba and Brazil.
Macadamia wood has a great ability to absorb manganese: its leaves and sap are rich in it.
The cuttings of this woody vegetation can be dried and its ash is a real "bio-mineral".
It is an extraordinarily high quality mineral, which can therefore be processed using normal hydrometallurgical strategies
Antony van der Ent, College of Queensland
Metallic farms
Nickel is a highly sought-after component in the modern era - it is vital in the manufacture of lithium-ion batteries and chromium steel.
A "metal farm" that tries to extract it from plants has long been active in Malaysia, developed by researchers from the College of Lorraine.
If you think it is a purely experimental project, consider that every year it collects between 200 and 300 kilos of nickel. Per hectare.
Nonetheless, it still takes time to create a new agromining supply chain
We hope this will contribute to a part of the nickel harvest, with a more environmentally sustainable approach. The "metal farms" have a future for this.
And also another possible field of application: that of the reclamation of former mining sites.
Other potential medical applications? Transforming metallic wood into biomass for food supplements (especially for zinc and selenium) or for "bio-forifiers" capable of enriching other crops.
In other words, agromining can be a singular alternative to agriculture.
The soil in massive components of theAustralia central, for example, is rich in selenium and the vegetation that develops there has proved to be an extraordinarily environmentally friendly hyperaccumulator.
