The U.S. Geological Survey (USGS) released the first hyperspectral data maps ever made on a country-wide level in July, giving the mining industry a full-scale view of the mineralogical spread in Afghanistan.
To create the map, data were collected in 2007 using a NASA aircraft – a WB-57 piloted by ex-space shuttle commanders – that was fitted with a HyMap hyperspectral sensor owned by Australian company HyVista Corporation. Rounding off the collaboration was the Afghan government, which approached the USGS in 2005 with funding of US$8.86 million for oil and gas, hyperspectral, airborne gravity and mag studies. Afghan officials are working hard to attract investors and junior miners to the region and the country’s Ministry of Mines is now using the maps in tender information packages.
“It was an opportunity for Afghanistan to rejuvenate the mineral sector for the revitalization of the economy, and USGS was tasked with collecting data,” said Trude King, project lead of hyperspectral data collection at USGS, adding that the country’s lack of humidity and barren landscape is the perfect environment for the technology. About 70 per cent of Afghanistan’s surface has now been mapped.
What sets this technology apart from traditional geophysical studies, King explained, is that collected data show the inner actions on the electron level of the minerals, enabling the identification of specific minerals and mineral assemblages.
The hyperspectral sensors used to create the maps measure unique spectral signatures for different minerals, which are matched to the USGS’ database. A user could, for instance, locate and quantify different types of building materials or minerals that might be present within an area of interest.
On the shortwave end of the spectrum, the USGS team examines how cations vary in the mineral structure. They look at absorption features resulting from overtones of fundamental vibrations of the crystallographic structure of the minerals in the longer wavelengths.
“When we look at this data, we can identify the intricacies of the composition, so we can tell several variations that are important in ore farming processes,” King said. “Mineral assemblages are identified so you can potentially tell what kind of materials are there – whether it is a gold deposit, copper porphyry or whether it is an iron deposit, for example.”
Having the majority of Afghanistan mapped out, with data available to the public, could reduce the cost for prospective juniors to access the region. Terry Cocks, managing director at HyVista, said that though there are other applications for the technology, such as monitoring wildfires or changes in tailings, the company’s day-to-day operations are dominated by mining company clients. Most of the company’s Australian work is done in the area of geological mapping and mineral exploration for juniors.
The cost of hyperspectral mapping is usually not prohibitive and can have major benefits for prospectors. For an area of 500 square kilometres at a flying height of 1.4 km, it took Lithex Resources of Western Australia approximately two months and AU$40,000 to identify the first group of targets for exploration at its Shaw River project. Brendan Borg, exploration manager at Lithex, explains that traditional geophysical methods were inadequate to get the results the company was looking for.
“There weren’t any other studies we could’ve used and it was such a large area, we could’ve gone out there and spent three or four months walking along the ground trying to find the targets,” he said. “For us, this has helped narrow down the search and that is why it is a good value proposition for us.”
In comparison, the area surveyed by the USGS – more than 450,000 square kilometres – is nearly 1,000 times the size of the Lithex survey. Cocks, of HyVista, explained that prices of surveys can vary widely and depend on location, size and scale of data being acquired, and what level of mapping is needed to meet a client’s exploration goals. For mineral exploration, semi-arid areas are best for these surveys.
“The sensor has to be able to see the rocks or soils and heavy vegetation makes that impossible,” Cocks said. “But surveys can still be successfully completed in the presence of some vegetation, say up to around 30 per cent to 40 per cent cover, and often this means choosing the dry season to undertake a survey.”
Outside of juniors, HyVista has also done mineral mapping projects for other state and federal geological surveys. Earlier this year, it surveyed about 11,000 square kilometres for ONHYM [the Geological Survey of Morocco] and since 2004, has worked with the Geological Survey of Namibia on several occasions.
Whether other jurisdictions will collect and display data on a level like Afghanistan remains to be seen, but the potential research and investment benefits are clear.