First ever diamond indicator plant discovered
A new plant which could help geologists in the hunt for diamonds has been uncovered in Africa.
Studies have uncovered an indicator plant, named Pandanus candelabrum, which has been found to grow only above kimberlite pipes, according to Economic Geology.
These kimberlite pipes typically play host to diamond bodies.
The plant itself was identified by Stephen Haggerty, a geophysicist who discovered the mineral haggertyite.
According to Haggerty, during exploration work in Liberia “an elusive diamond-bearing kimberlite pipe was located, [as] a bonus to the pipe location is that an unusual botanical indicator, Pandanus candelabrum, is now recognised exclusively on the pipe and not in eluvium covering the adjacent kimberlite dike”.
“The identification of Pandanus candelabrum,with stilt-like aerial roots, is the first plant to be described that has a marked affinity for kimberlite pipes,” Haggerty said.
“This could dramatically change the exploration dynamics for diamonds in West Africa, as geobotanical mapping and sampling is cost-effective in tough terrain.”
Using plants to identify deposits, a term commonly known as geobotany, has a long history in mining.
Previously plants known thrive in soils with heavy metals were used to uncover metal deposits.
The technique has been recorded as being used in China since the 5th century BC, and in fact Sweden’s former Viscaria copper mine was actually named after the Viscaria aplina flower which prospectors used to discover the deposit, as the flower is known to grow in soils with heavy copper concentrations.
Australian natives such as Stackhouse tyronii and Hybanthus floribundus can also be used as lead and nickel indicators due to their hyperaccumulator ability, according to The Lead Group and to research carried out by CQ University professor Nanjappa Ashwatha and Dr. Poonam Bhatia.
In fact “Stackhousia tryonii is a serpentine-endemic, rare, native Australian plant and is reported to hyperaccumulate nickel up to 55,500 mg g-1 on a dry weight basis,” the group explained.
In Africa, ancient African civilisations used termites and their enormous mounds as a starting place for prospecting and uncovering deposits.
As termites continually search for water they can often dig down to depths of more than 70 metres and distances of hundreds of metres.
“Termites are nature’s little drillers,” researcher and University of Adelaide geoscientist Anna Petts explained at the Geological Society of Australia’s Earth Science Showcase.
“Termites conveniently bring subterranean soil samples to ground level to construct or fix their mounds.
“So by simply taking a sample of a termite mound, geologists can gain a good idea as to what minerals and metals can be found in the ground beneath it – making it a much cheaper way to undertake preliminary soil testing for minerals exploration,” she said.
“More intensive testing can then be undertaken if a site looks promising.”
This method was used to find the Vila Manica copper deposit in Mozambique in 1973, while the massive Jwaneng diamond mine was also reportedly found by termite mound sampling.
Research in science journals PLoSONE and Geochemistry: Exploration, Environment, Analysis has also found at test sites in the WA Goldfields that termite mounds contained high concentrations of gold, indicating larger deposits underneath.
“We’re using insects to help find new gold and other mineral deposits. These resources are becoming increasingly hard to find because much of the Australian landscape is covered by a layer of eroded material that masks what’s going on deeper underground,” Aaron Stewart, a CSIRO entomologist, said.
He explained that “the insects bring up small particles that contain gold from the deposit’s fingerprint, or halo, and effectively stockpile it in their mounds.