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The follow up question is, how come the different elements aren't uniformly mixed within the earth. Or perhaps formed into stratified layers with the densest at

The follow up question is, how come the different elements aren't uniformly mixed within the earth. Or perhaps formed into stratified layers with the densest at the centre? E.g. Why are there 'deposits' of gold relatively close to the surface? Something to do with interaction of the physical and chemical properties of the elements with local variations in conditions?

changoplatanero 6y ago
Yes you're right. Geologic and biologic processes unevenly distribute the elements
- HarryHirsch 6y ago
  The keyword is "Goldschmidt classification": https://en.wikipedia.org/wiki/Goldschmidt_classification https://en.wikipedia.org/wiki/Goldschmidt_classification Those who would like to know more could do worse than pick up Greenwood's & Earnshaw's book (this one: https://www.amazon.com/-/dp/0750633654 https://www.amazon.com/-/dp/0750633654) from the nearest university library, it has a chapter on nucleogenesis and cosmic and geologic abundances.
ncmncm 6y ago
All Earth's primordial gold sank. So, all the gold we find or mine came from meteorites (including dust) after solidification. Most has been dissolved in water.
dredmorbius 6y ago
The Earth is mostly stratified: light rocky silicate crust, heavier (though also rocky) magnesium-silicate mantle, core of mostly nickle-iron and heavier elements, which formed during the iron catastrophe. Crustal deposits of heavier minerals largely result from late bombardment (after the crust had formed, about 100 million years after Earth's formation itself), geothermal and tectonic activity (volcanism, rift zones, vents), and biological mobilisation and concentration (e.g., lighter elements in coal and limestone, but notably, banded iron formations). Events such as the hypothesized Tethys collision could of course also have influenced distribution. Gold forms veins typically in quartzes through differential precipitation AFAIU. Ore formation is its own fascinating subfield of geology, and is underappreciated by many advocates of space mining. https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth... https://en.wikipedia.org/wiki/Planetary_differentiation https://en.wikipedia.org/wiki/Planetary_differentiation https://en.wikipedia.org/wiki/Iron_catastrophe https://en.wikipedia.org/wiki/Iron_catastrophe https://en.wikipedia.org/wiki/Ore_genesis https://en.wikipedia.org/wiki/Ore_genesis

changoplatanero 6y ago

Yes you're right. Geologic and biologic processes unevenly distribute the elements

HarryHirsch 6y ago
The keyword is "Goldschmidt classification": https://en.wikipedia.org/wiki/Goldschmidt_classification https://en.wikipedia.org/wiki/Goldschmidt_classification Those who would like to know more could do worse than pick up Greenwood's & Earnshaw's book (this one: https://www.amazon.com/-/dp/0750633654 https://www.amazon.com/-/dp/0750633654) from the nearest university library, it has a chapter on nucleogenesis and cosmic and geologic abundances.

ncmncm 6y ago

All Earth's primordial gold sank. So, all the gold we find or mine came from meteorites (including dust) after solidification. Most has been dissolved in water.

dredmorbius 6y ago

The Earth is mostly stratified: light rocky silicate crust, heavier (though also rocky) magnesium-silicate mantle, core of mostly nickle-iron and heavier elements, which formed during the iron catastrophe. Crustal deposits of heavier minerals largely result from late bombardment (after the crust had formed, about 100 million years after Earth's formation itself), geothermal and tectonic activity (volcanism, rift zones, vents), and biological mobilisation and concentration (e.g., lighter elements in coal and limestone, but notably, banded iron formations). Events such as the hypothesized Tethys collision could of course also have influenced distribution. Gold forms veins typically in quartzes through differential precipitation AFAIU. Ore formation is its own fascinating subfield of geology, and is underappreciated by many advocates of space mining. https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth... https://en.wikipedia.org/wiki/Planetary_differentiation https://en.wikipedia.org/wiki/Planetary_differentiation https://en.wikipedia.org/wiki/Iron_catastrophe https://en.wikipedia.org/wiki/Iron_catastrophe https://en.wikipedia.org/wiki/Ore_genesis https://en.wikipedia.org/wiki/Ore_genesis