With so much discussion these days about shortages of Rare Earth and Minor Industrial Metals including Indium, one basic question is rarely addressed for users of Indium: If there is a shortage of Indium, why don’t they just open more Indium mines?
We’ve heard quite a bit of news about various countries feeling China’s squeeze on rare Earth supply and starting new Rare Earth mining projects. But where are the new Indium mining projects?
The reason why there are no Indium mines, is that Indium occurs in very low concentrations in the Earth’s crust. Mining and refining costs money, so that the value of any metal ore dug out of the ground has to exceed the cost of digging it out and refining it to market standard purities. In Indium’s case the market standard is 99.99% pure (100 parts per million impurities). However, even this standard does not tell the whole story, as 99.99% is the standard for low-tech applications such as low melting point alloys. The real demand is for hi-tech applications, which require purities of at least 99.995%, with some demanding 99.999% or 99.9999% and higher for semiconductor use.
If one scans the internet, there are many junior mining companies trumpeting the detection of Indium in their test samples.
Here is a recent announcement:
What sets this project apart from other properties are the exceptionally high surface grades in silver, zinc, lead and indium. Although our sampling on the project to date is limited, it is very encouraging. For instance, on the western vein, two channel samples were collected that graded 760 gpt silver, 15.6% zinc, 7.2% lead and 153 ppm indium, and 1,981 gpt silver, 33.1% zinc, 5.6% lead and 430 ppm indium, respectively. On the eastern vein, a channel sample graded 678 gpt silver, 15.0% zinc, 4.5% lead and 12 ppm indium.
So this company is happy that the Indium concentrations are so high. Please note that the zinc concentration is very high, and zinc and indium are typically found together.
But I’d like to break down these figures so that the concentrations can be compared apples to apples:
The sets of numbers, translated into parts per million, so that we can really compare the Indium to the other metals shows:
Sample #1 Sample #2 Sample #3 Average
Zinc: 156,000 ppm Zinc: 331,000 ppm Zinc: 150,000 ppm Zinc: 212,333 ppm
Lead: 72,000 ppm Lead: 56,000 ppm Lead: 45,000 ppm Lead: 57,666 ppm
Silver: 760 ppm Silver: 1,981 ppm Silver: 678 ppm Silver: 1140 ppm
Indium: 153ppm Indium: 430 ppm Indium: 12 ppm Indium: 198 ppm
In this case, the Zinc is 1000 times more prevalent than Indium, and in Sample #3, 10,000 times more so.
So for every million pounds of dirt pulled out of the ground, 212,000 pounds will be zinc, 57,000 pounds will be lead, 1,140 pounds will be silver, and only 198 pounds (less than 100kg) of that million pounds, will be indium.
This is why Indium is produced mainly as a co-product of Zinc mining, and to lesser extents Copper, Tin and Lead mining. When demand for Zinc is down, supply of Indium is down, even when demand for Indium is high. Even if demand for Zinc increases, say triple, and three million pounds of dirt is pulled out the ground instead of one million, buyers for 636,000 pounds of zinc have to be found, in order for less than 600 pounds of Indium to be supplied to the market.
In economic terms, this relationship will not change even if Indium reaches $10,000/kg or even $25,000/kg, because a million pounds of dirt, is a lot of dirt.
