Fortunately, other minerals are more plentiful within the rock, and can provide a clue to both the whereabouts of the source pipe, as well as the likelihood of it being diamondiferous. These minerals include garnet, clinopyroxene, orthopyroxene, olivine, spinel, ilmenite, magnetite, rutile, and zircon. Perhaps the most important of these minerals is garnet, or more specifically, a special member of the garnet family known as pyrope. In diamond exploration, these stones are often referred to as G9 or G10 garnets, depending on the concentration of Chromium Oxide.
What makes the garnet special is that it forms under the same temperature and pressure conditions as diamond, within the same diamond stability zone in the asthenosphere. In fact, G10 garnet is frequently an inclusion inside a diamond, indicating that they form alongside each other. Finding large concentrations of G10 garnet can be a good indication of a diamondiferous kimberlite. On the Mohs hardness scale, garnet has a hardness of 8, compared with diamonds, which have a hardness of As a relatively hard mineral, garnet stands up against the heavy weathering and erosion that takes place over millions of years.
Therefore, many of the garnets that travelled alongside diamond within a kimberlite remain intact on the surface and can be used to pinpoint the source, or at least significantly narrow down the search. If geologists know which direction erosion or weathering is likely to have taken, such as the action of glacial movements or tidal water flows, they can use the dispersion of indicator minerals to reverse engineer the likely location of the source.
The resulting mineral dispersion can be seen visually as a pathway, often referred to as an indicator mineral train. Ground geophysical sampling is a challenging and expensive process.
It involves taking random samples of rock at various distances within areas of interest. In the more high-activity exploration areas, such as Canada, Russia, and Botswana, this work has been ongoing for many years and data can sometimes be available on historical mineral sampling. However this is still a very high-risk activity, and many companies run out of money before they discover anything of interest.
Geologists have also developed techniques to sample from the sky, which allows them to cover a much wider area in a shorter period of time. Offering an explanation, Geology. As is mentioned, the intense heat and pressure of the deep mantle combine to transform this carbon into diamonds.
As more carbon atoms come into the vicinity of the bonded carbon atoms, they too attach. Eventually, once enough carbon atoms have attached to one another, diamonds are formed. Colored diamonds are created when foreign particulates are trapped during the diamond crystallization process. Traces of different material result in different hues , as well as different hue intensities. For example, blue diamonds, which are incredibly valuable, are created when boron is introduced in the diamond formation process — it bonds to the carbon atoms, absorbing the red, yellow and green areas of the color spectrum.
Kimberlite pipes were first found near Kimberley in South Africa, but since then they have been found on most continents. Of course, as has been noted, not all kimberlite pipes are created equal and only a small percentage of them contain diamonds.
So where should diamond exploration companies look if they want to find kimberlite pipes that contain diamonds? That said, simply showing up in a country that produces diamonds and hoping to find a kimberlite field is not a sound approach.
When a company has found a site that it believes may hold diamonds, one thing it may do is look for minerals that are associated with kimberlite pipes. These minerals include garnet, clinopyroxene, orthopyroxene, olivine, spinel, ilmenite, magnetite, rutile and zircon. A member of the garnet family called pyrope is one of the best when looking for diamonds. In fact, it's theorized that the only place the plant grows is above columns of kimberlite.
So find the plant, potentially find a kimberlite tube. Find a tube and you just might find some diamonds. The man who uncovered the plant's kimberlite-loving nature is Stephen Haggerty , a researcher at Florida International University in Miami. His discovery appears in the current issue of the journal Economic Geology.
Haggerty, who's also the chief exploration officer of Youssef Diamond Mining Company which owns mining concessions in Liberia , told Science magazine that while the plant is a good indicator of a kimberlite pipe, it's good to follow a rule of sixes to determine which pipes will hold diamonds. If the plant is as choosy as it seems to be, diamond hunters in West Africa will have a simple, powerful way of finding diamond-rich deposits.
Botanists and geologists have long known that certain plants have evolved to grow on specialized soils. Hand also points out that not only could the palm-like plant serve as a living signpost for prospectors, it could also minimize some of the environmental impact of diamond mining in West Africa.
Rather than relying on costly strip mining, companies could instead focus their efforts on kimberlite pipes, which are now much easier to find.
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