3 ms·

Which leads to another interesting question, why is cobalt (or anything else) heterogeneously distrubuted in the earth’s crust? The answer is probably too long

• philipkglass 8y ago
  Largest factor: the abundance of liquid water and associated chemical effects. Second largest factor: the existence of living organisms that also alter the chemical environment. For example, lead sulfide is nigh-insoluble in water, so where water containing dissolved lead meets water containing dissolved sulfide, a concentrated ore body of lead sulfide (galena) can form. Sulfate anions are more common in Earth's natural waters than sulfide anions, but so-called sulfur reducing bacteria convert sulfate into sulfide as part of their respiratory cycle. That's an example of the biological contribution to ore body formation. As an element in Earth's crust, lead is actually rarer than so-called rare earth elements like neodymium. But neodymium's aqueous chemistry doesn't offer such common opportunities for concentration as lead, so in practice useful ore bodies of lead are much more common than those of neodymium. The lack of liquid water on other celestial bodies is why they don't form ore bodies like on Earth. On the Moon and Mercury, for example, one would expect to find no economically exploitable deposits of either lead or neodymium.