Fig. 1.  Most-common elements in the Earth’s crust

Once upon a time ...

Isn’t that how most fairy tales start? I’ve long held the belief that in the near future the location of and accessibility to minerals found around the globe will give certain nations not only strategic advantages but tremendous leverage and perhaps yet-to-be-realized bargaining power as global economic leaders. The United States, now positioned as the world’s second largest consumer of raw materials, is painfully aware of our interdependence on foreign sources. It’s time for the rest of us to learn more.   

Let’s begin by considering the Earth as a whole. When we do, we find the planet consists of the following elements (listed in order of how plentiful an element is) by percentage:  

1. Iron -- 32%
2. Oxygen -- 30%
3. Silicon -- 15%
4. Magnesium -- 14%
5. Sulfur -- 3%
6. Nickel -- 2%
7. Calcium -- 2%
8. Aluminum -- 1%
9. All others -- 1%    

If we now focus on the Earth's crust (Fig. 1), we find the following elements and percentages:  

1. Oxygen -- 47%
2. Silicon -- 28%
3. Aluminum -- 8%
4. Iron -- 5%
5. Calcium -- 4%
6. Sodium -- 3%
7. Potassium -- 3%
8. Magnesium -- 2%
9. Titanium -- 0.5%
10. All others  --  < 1%  

Perhaps surprisingly, most other common metallic elements are far less plentiful in the Earth’s crust, including:  

1. Chromium -- 0.01%
2. Cobalt -- 0.003%
3. Copper -- 0.005%
4. Lead --   < 0.001%
5. Manganese --   < 0.10%
6. Nickel -- 0.007%
7. Platinum -- 0.0000001%      
8. Vanadium -- 0.02%
9. Zinc -- 0.004%

Fig. 2. U.S. dependence on foreign sources for minerals

As all of us know, elements are mined all over the world. What we perhaps don’t realize, or appreciate, is that the mineral resources of the U.S. are significantly lacking in many key areas, increasing our global dependence (Fig. 2).