I originally thought that you can only find certain things like iron, copper, and other things in certain places in the world and deep in mines but I saw in a few YouTube videos that you can find iron in rocks just laying on the ground. I searched for where copper comes from and it seems that, even though a lot of it comes from Chile, it can be found everywhere in smaller amounts. Is this true? Could I walk out into the woods right now anywhere in the world and find copper and iron?
$\begingroup$
$\endgroup$
1
-
2$\begingroup$ Grab a strong magnet, tie it to a string, and drag it through the woods. I'm willing to bet you will pick up small bits of iron. $\endgroup$– rtaftDec 14, 2020 at 18:08
Add a comment
|
3 Answers
$\begingroup$
$\endgroup$
Metals occur on every continent . The issue is whether or not they occur in sufficiently large deposits for them to be mined economically.
The difference between a mineral deposit and an ore body is economics: can it be mined for a profit?
One of the issues with mineral resources is that once they've been mined, they're gone.
Cornwall and Devon, in the UK, were once a significant producer of tin and copper.
Spain is major source of metals in Europe. Some of its mines were started by the ancient Romans. Poland too, has a active mining industry, as does Sweden.
Chile and Peru are major sources of copper, but copper is also mined in the US, Zambia, Australia and Russia.
Africa has a well established mining industry that mines many metals: gold, copper, iron, lead, zinc and platinum.
Metal mining in Australia and Canada provide both countries with significant sources of export income.
China has iron ore deposits that grade between 25 and 40 percent iron, but it prefers to buy higher grade iron ore, grading 65 to 70 percent iron, from elsewhere, mostly from Brazil, Australia and South Africa, because it is cheaper to produce steel from higher grade ore.
However, mineable quantities of some metals, such as lithium, platinum and rare earth metals tend to be concentrated in specific locations.
$\begingroup$
$\endgroup$
5
All stable elements (and the radioactive U and Th) exist everywhere on Earth. They're in the sand underneath your feet, they're in your bones, they're in the dust in the air, they're in the ocean. The question is how much.
There are some estimates on the concentration of each element, and there's a nice table that lists all of them in Wikipedia article Abundance of elements in Earth's crust.
I searched for where copper comes from and it seems that, even though a lot of it comes from Chile, it can be found everywhere in smaller amounts. Is this true?
Yes, this is very true. If you look up the table, you can see that estimates for copper are between 50 and 100 parts per million. This equals to 0.005% to 0.01%. This leads to your next question:
Could I walk out into the woods right now anywhere in the world and find copper and iron?
Yes, you will find copper. But assuming it's just an average rock, copper will only be 0.01%. This is very unremarkable and useless. You will probably not even be able to see it or detect it unless you have specialised instruments. Other than copper, it will have much more of many other elements.
This leads to the discussion of ore deposits. What is special about places like Chile, where in certain places you can have 1% of copper, instead of 0.01%? This is hundred times more abundant than in the average crust, and there's enough copper in there so its sale value covers for the cost of mining it, and leads to additional profit. The answer is in the exciting field of ore deposit geology, which employs many people in governments, industry, and academia.
-
1$\begingroup$ By unremarkable, do you mean like size of a seed unremarkable or smaller like so small you couldn’t even find it if you smelted the rock to pull out the metal? $\endgroup$ Dec 15, 2020 at 0:31
-
1$\begingroup$ Most likely that the copper will be as impurities in other, more common, minerals. You will not find metallic pure copper, no matter how hard you look (although it varies). It is possible to eventually smelt the rock and extract the copper, but it will be a very laborious and expensive process, which is why we don't do it. You will end up using more copper in the extraction machinery than you will actually be able to extract from the rock. $\endgroup$– GimelistDec 15, 2020 at 0:34
-
1$\begingroup$ @Gimelist: But sometimes we do. E.g. the gold ore mined in the Carlin trend contains less than 1 part in 100,000 of gold: en.wikipedia.org/wiki/Carlin%E2%80%93type_gold_deposit OTOH, you can - or once could - find large masses of native copper in places like Michigan: en.wikipedia.org/wiki/Native_metal#Copper $\endgroup$– jamesqfDec 16, 2020 at 0:27
-
1$\begingroup$ @jamesqf 1 part in 100000 is 10 ppm - which is about a thousand times more abundant than "average crust". 10 ppm, although it doesn't sound like much, is concentrated enough to be mined at a profit. And yes, here and there you can find chunks of copper. Very uncommon though, and not characteristic of "average crust". $\endgroup$– GimelistDec 16, 2020 at 0:35
-
1$\begingroup$ @Gimelist: That was kind of my point, that there aren't really a lot of "average" rocks out there. Earth's a dynamic place (and has been so for 4 billion years or so), and things have gotten differentiated a lot. $\endgroup$– jamesqfDec 17, 2020 at 2:21
$\begingroup$
$\endgroup$
Part of the problem is in the question itself. In the title, you ask about "in every continent" while in the text, you imply that you are talking about smaller areas.
One premise we can safely assume is that most elements are distributed unevenly. That is a far more relaxed question than you are asking, though.
For an example, look at hydrogen.
You will find a lot more hydrogen in a cubic meter of ocean water than in the same amount of Sahara sand away from the Nile river (but not zero - there still is water in even the driest parts of the Sahara, and hydrogen could also be part of some of other chemical compounds found there).
But there are lakes and waterfalls on the same continent as the Sahara desert, so the continent of Africa contains a lot more hydrogen than the Sahara desert.
You can apply similar reasoning to most elements.
So if you are truly asking about continents, the answer is likely: "pretty much every element will be found somewhere on each continent".
As you get more granular, it becomes more difficult to answer. It is theoretically conceivable that there might be one cubic meter of earth surface that is missing some elements. In the spirit of your question, I don't think we should go more granular than that. And I'm also only looking at "stuff" near or above the surface of the earth, say, within range of mining or drilling.
The next part of the question is, which elements are candidates for missing completely?
If an element (or a compound containing it) is water-soluble, odds are that after 4 billion years, it has distributed through nearly all water (with the possible exception of rain water, which has been distilled and only picked up materials suspended in the atmosphere). And since water is pretty much everywhere on earth, anything that is water soluble probably found its way, in minute quantities, in every crevice.
The best candidates for insolubility would probably be noble gases and certain metals. But even those are, to a small extent, soluble. I am not aware of any element that is absolutely insoluble in water in any form.
So the answer to your question is likely: while it is theoretically possible that there are a few spots (of more than one cubic meter) that do not contain any of a particular non-radioactive element, it is exceedingly unlikely. Materials on earth just have been too thoroughly mixed.
