# Why are cobalt deposits so unevenly distributed?

The Democratic Republic of the Congo's Katanga Province contains almost 40% of the world's reserves of cobalt [1].

Why are deposits concentrated so strongly in such a small portion of the earth?

I would have thought that this is due to similar reasons to: Why do gold deposits form only in certain areas of the earth?

But the distribution of cobalt seems far more uneven than that of gold.

Do the geological processes causing this uneven distribution significantly differ from those that cause the uneven distribution of gold?

[1]: British geological survey, 2009

• More up to date figures from the US Geological Survey 2021. Congo has 50% or known reserves, Australia 19.7% & Cuba 7%.
– Fred
May 16 at 23:13
• – Fred
May 16 at 23:48
• Based on a very small sample size. If the deposits in the Congo are similar to Kalongwe, with an average grade of cobalt of 0.72% compared to the average grade at Murrin Murrin in Australia with an average Co grade of 0.085%, the deposits in the Congo are much richer than elsewhere & thus contain more Co per quantity of host rock. The average ore grade for DRC deposits is in the range from 0.17% to 0.25% Co.
– Fred
May 17 at 0:01
• Cobalt—Styles of Deposits and the Search for Primary Deposits states the cobalt grades of Congo deposits is higher than elsewhere: 0.1%-1.1% for the Congo compared to 0.01% to 0.21% elsewhere, pp114-16.
– Fred
May 17 at 0:14
• Related, for lithium: earthscience.stackexchange.com/q/14091/2643
– Mark
May 18 at 1:59

## Part 1

The Democratic Republic of the Congo's Katanga Province contains almost 40% of the world's reserves of cobalt [1].

Why are deposits concentrated so strongly in such a small portion of the earth?

Cobalt isn't as unevenly distributed as it seems. It is correct that most of the world's cobalt reserves are in DRC, but most of the cobalt resources are not in DRC. And this is a very important point.

Resources are known and estimated quantities of economically extractable materials. Reserves are resources for which detailed plans for extraction have been made. This means that to turn a resource into a reserve you need to have plans for the extraction and refining plants, have environmental approval, have the workforce figured out, have authorisation from the owners of the land, and more. As you can guess, making a resource into a reserve is a time consuming and expensive process.

The reason why most of the Earth's reserves are in DRC is simply because it's easier and cheaper. The infrastructure already exists, and the expertise exists. At current technology levels and cobalt prices, the investment in defining a reserve from a resource elsewhere is simply not economical.

This does not mean that DRC has most of the cobalt. It only means that getting cobalt out of the ground and making it into a product is cheaper in DRC than it is in other countries.

## Part 2

Do the geological processes causing this uneven distribution significantly differ from those that cause the uneven distribution of gold?

The reasons are the same, in principle. Every element behaves differently and will separate from other elements and concentrate because of various geological processes. Cobalt tends to follow copper and nickel, and in most cases it is mined as a by-product of those elements. That's why cobalt is extracted from the African Copperbelt, and why it's extracted from nickel deposits in Australia. Not much point going into the chemistry and thermodynamics of why this happens, but the point is that elements which are concentrated by rare geological processes will be found in fewer places, and elements that are concentrated by common geological processes will be found in more places.

• "Reserves vs resources" Seems like this is the same conversation as to when we start pulling oil from the Tar Sands in Canada - we know it's there but it's only used when prices are above X (because it's not profitable under a certain price) May 18 at 4:38
• I guess we don’t know half of what is beneath the oceans, but above sea level, what processes are concentrating certain elements to specific places? May 18 at 7:54
• @Johnny that's more than can fit in a StackExchange answer, and dependent on element. There were many books and papers written about these topics. May 18 at 11:25
• For a bit of scale, the gold deposits mined in the Carlin Trend (Nevada) contain 0.2-0.25 ounces of gold per ton of ore. That's 0.001% or less. So for gold, an economically mineable ore is much less concentrated than one might think. But gold is currently at $1867/oz, cobalt at$1.38. May 17 at 17:21