Copper ore, for instance, often contains molybdenum, rhenium, selenium, tellurium, along with small amounts of rare-earth elements.
Second, like many metals, rhenium occurs naturally in specific pockets.
In principle, aircraft do not need rhenium to stay aloft.
It was set up as the result of a European research project called BioShale, which showed that bacteria could recover nickel, copper, lead, silver, zinc, cobalt, rhenium, selenium, tin, gold, platinum, palladium and uranium from Europe's extensive but underexploited "black shale" deposits.
Those that do not, such as technetium and americium, have been substituted, respectively, by rhenium and neodymium, which have similar traits.
Unlike over one-third of all metals, rhenium has actually seen a rise in recycling rates (although less than a quarter of the stuff found in new jet engines is second-hand).
But on the advice of Ekaterina Dadachova, a radiologist and one of the paper's authors, they eventually plumped for attaching a radioactive isotope of rhenium to their bugs.Radioactive rhenium is commonly used in conventional radiotherapy.
The vast majority of global rhenium is produced in just two countries, Chile and Kazakhstan.
READERS may be forgiven for not having heard of rhenium (chemical symbol Re).
General Electric, one of the world's biggest makers of jet engines, has spent years developing nickel-based superalloys to replace rhenium.
Ida Noddack, a German chemist, codiscovered the chemical element rhenium and first proposed the idea of nuclear fission.
