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The earliest stage in the diamond process is, of course, mine exploration. This is arguably the most challenging stage of our business, as the hidden locations of diamond mines are not always obvious to even the most skilled geologists. It really is akin to looking for a needle in a haystack, but new technology promises to make the haystack a little smaller, and the needle a little more obvious.
Magnetic surveying has been used in the diamond industry for decades. Kimberlites are ultramafic rocks that usually have high density, high magnetic susceptibility, and high electrical conductivity relative to surrounding rocks, and therefore typically show a different electro-magnetic signature to their surrounding host rock. An airborne survey, often achieved with a camera mounted to a helicopter or remote controlled drone, can capture data from a wide area in a small amount of time, and pinpoint electromagnetic anomalies. However, this technology yields a lot of false-positives, and can also fail to spot a diamond deposit that had a slower journey to the surface, and has therefore absorbed a lot of surrounding host rock material. High-frequency seismic reflection technology and ground penetrating radar have the potential change this.
Seismic reflection was initially developed to help scientists better understand earthquakes, but it has been used successfully in oil and gas exploration, and now has potential to help look for diamonds and other minerals. The technology still needs further development, as it is principally used to delineate larger structures under the Earth's surface, too big for a relatively small kimberlite deposit. But with advancements and testing, the frequency range of seismic reflection tools is increasing, which allows for a much higher level of accuracy, on the scale of a hidden kimberlite. Simply put, high frequency seismic waves are transmitted through the ground. These waves travel at different speeds through different types of rock, and have the ability to penetrate deep within the Earth's surface, to depths below 100 km. The data can then be used to determine which rock types might more likely be kimberlite, and to then direct ground geophysics and drilling teams.
Ground penetrating radar is more limited than seismic reflection in its ability to penetrate deep under the ground, but it has a high degree of accuracy. Radar seeks to find small anomalous cracks and crevices in the host rock, just like the space that would be occupied by a diamond or other mineral crystal. According to case studies by Jeffrey Patterson and Frederick Cook, a radar pulse with a frequency of 1 GHz that has a wavelength of about 10 cm may be able to resolve features as small as 2.5 cm in size. Although identifying a crystal size of 2.5 cm is still too large to be practically useful in diamond exploration, it seems like only a matter of time before the technology can be refined to enough to become a promising new tool for our industry.
International space agencies are providing a host of new satellite mapping technologies, which are available to mineral explorers. Some of these technologies include the Landsat thematic mapper and the enhanced thematic mapper multispectral imager by the United States, and high-resolution panchromatic imaging technology (SPOT), developed by the French space agency. The US government has transferred some of these existing technologies to the commercial sector, and several-privately owned satellites are currently in operation, providing detailed (four-meter resolution) multispectral imagery.
Despite advances in airborne exploration, very little advancement has been made in on-the-ground drilling in the past three decades. All diamond exploration activity must eventually lead to drilling, in order to confirm the presence of a kimberlite, to take samples to determine the presence of diamonds, and to estimate grade and diamond value. This contrasts with massive improvements in drilling for oil and gas, such as those that have made hydraulic fracturing ('fracking') a viable technology in natural gas mining. However, an unlikely source may deliver the next quantum leap in small diameter drilling, which is an essential but very costly element of diamond exploration.
For years, NASA has been researching new drilling techniques for the exploration of Mars that will allow them to take samples from deep below the surface of the red planet, without the luxury of enormous drilling equipment, which would be difficult and costly to transport into space. Much of their work is based on miniaturization of existing technology, such as the technique of down-hole logging used in petroleum exploration. Although effective miniaturization might still be years away, it offers the potential to make diamond exploration much cheaper than it is today, which would open up the ability for exploration companies to research significantly more potential diamond deposits than they can currently.
Unfortunately, the exploration budget of most major diamond producers has been steadily declining for years. Exploration today tends to be focused almost entirely within previously discovered diamond districts, such as the Orapa district in Botswana, the Slave region in northern Canada, or the Arkhangelsk district in Russia. However, there is hope that technologies that are currently being developed in other commercial industries, as well as by governments around the world, could soon be used in our industry to discover the Earth's next mega-pit diamond deposit.
Just like in diamond exploration, diamond recovery has seen the implementation of new technologies that are changing the way diamonds are liberated from their host rock ore. We will discuss some of these new developments next week.