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>Iron is the most abundant element on Earth. No, it's not. I'm pretty sure it's silicon. Iron is relatively rare (but not as rare as platinum or gold of cour

by magduf 8y ago

>Iron is the most abundant element on Earth. No, it's not. I'm pretty sure it's silicon. Iron is relatively rare (but not as rare as platinum or gold of course). Iron is the most abundant element in the Earth, but not on it. The core is full of iron. But that doesn't help us at all, because we can't get to that. We can only access materials in the crust, and there isn't much iron there.

pdonis 8y ago
> I'm pretty sure it's silicon If you include the biosphere, it's carbon. If you include the oceans, it's hydrogen (the hydrogen atoms in water). Even if you just include inorganic materials in the crust, I believe oxygen is more abundant than silicon (oxygen is part of silicate rocks).
- magduf 8y ago
  Yeah, you're right about oxygen, I should have said silicon is the most abundant mineral. But you're wrong about the rest: https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements#Crust https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elem... Oxygen is #1, silicon is #2, aluminum is #3, and iron is #4 (though far less than O or Si). Carbon doesn't even rank in the top 9.
  - pdonis 8y ago
    > you're wrong about the rest It says "in the Earth's crust". That indicates to me that the biosphere and the oceans are not being counted. Also, it's giving abundances by mass, which is not the only way to do it (I was actually thinking of abundance by atom count). Later in the same Wikipedia article, the top eleven abundances by mass for the ocean are given: oxygen and hydrogen are the first two, carbon is #10, and silicon doesn't even make the list. No figures are given in that article for the biosphere; my statement of carbon being the most abundant for that is based on the fact that it forms the "backbone" of all of the main types of molecules in living organisms: proteins, carbohydrates, lipids, and nucleic acids.
    - magduf 8y ago
      Carbon may be the "backbone" of organic matter, but that doesn't equate to the Earth's crust having a lot of it. Iron is the "backbone" of our red blood cells, but that doesn't mean we actually have that much iron (by mass) in our bodies or even our blood. As for the "crust", the definition of the Earth's crust I'm pretty sure includes the oceans, the seafloor, and everything down to the mantle, so the biosphere and oceans should be counted there. Hydrogen doesn't rank highly because it has little mass compared to other elements. Atom count seems like a pretty pointless metric; we're talking about resources available for mining, in which case mass is what counts. Of course silicon doesn't make the list for oceans because it's mostly water, and a lot of dissolved CO2. Count the seafloor and you'll find lots of silicon (and probably some iron, aluminum, titanium, etc.).
      - pdonis 8y ago
        > the definition of the Earth's crust I'm pretty sure includes the oceans, the seafloor, and everything down to the mantle If the crust included the oceans, there wouldn't be different figures for the oceans in the same article. You make a valid point about the seafloor being part of the crust; but I didn't intend to include the seafloor in "oceans". > Atom count seems like a pretty pointless metric; we're talking about resources available for mining, in which case mass is what counts. That depends on what we're mining the resource for. For example, if we're mining for metals to use in catalytic converters for vehicles, atom count is the relevant metric, since the catalytic effectiveness depends on the number of atoms, not on the total mass.
      - pdonis 8y ago
        > Iron is the "backbone" of our red blood cells No, it isn't; each hemoglobin molecule has just four iron atoms in it (IIRC--each heme structure has one, and I think there are four heme structures in one hemoglobin molecule). Most of each such molecule, by either mass or atom count, is carbon. And each red blood cell is more than just hemoglobin molecules.

by magduf 8y ago

pdonis 8y ago

> I'm pretty sure it's silicon If you include the biosphere, it's carbon. If you include the oceans, it's hydrogen (the hydrogen atoms in water). Even if you just include inorganic materials in the crust, I believe oxygen is more abundant than silicon (oxygen is part of silicate rocks).

magduf 8y ago
Yeah, you're right about oxygen, I should have said silicon is the most abundant mineral. But you're wrong about the rest: https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements#Crust https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elem... Oxygen is #1, silicon is #2, aluminum is #3, and iron is #4 (though far less than O or Si). Carbon doesn't even rank in the top 9.
- pdonis 8y ago
  > you're wrong about the rest It says "in the Earth's crust". That indicates to me that the biosphere and the oceans are not being counted. Also, it's giving abundances by mass, which is not the only way to do it (I was actually thinking of abundance by atom count). Later in the same Wikipedia article, the top eleven abundances by mass for the ocean are given: oxygen and hydrogen are the first two, carbon is #10, and silicon doesn't even make the list. No figures are given in that article for the biosphere; my statement of carbon being the most abundant for that is based on the fact that it forms the "backbone" of all of the main types of molecules in living organisms: proteins, carbohydrates, lipids, and nucleic acids.
  - magduf 8y ago
    Carbon may be the "backbone" of organic matter, but that doesn't equate to the Earth's crust having a lot of it. Iron is the "backbone" of our red blood cells, but that doesn't mean we actually have that much iron (by mass) in our bodies or even our blood. As for the "crust", the definition of the Earth's crust I'm pretty sure includes the oceans, the seafloor, and everything down to the mantle, so the biosphere and oceans should be counted there. Hydrogen doesn't rank highly because it has little mass compared to other elements. Atom count seems like a pretty pointless metric; we're talking about resources available for mining, in which case mass is what counts. Of course silicon doesn't make the list for oceans because it's mostly water, and a lot of dissolved CO2. Count the seafloor and you'll find lots of silicon (and probably some iron, aluminum, titanium, etc.).
    - pdonis 8y ago
      > the definition of the Earth's crust I'm pretty sure includes the oceans, the seafloor, and everything down to the mantle If the crust included the oceans, there wouldn't be different figures for the oceans in the same article. You make a valid point about the seafloor being part of the crust; but I didn't intend to include the seafloor in "oceans". > Atom count seems like a pretty pointless metric; we're talking about resources available for mining, in which case mass is what counts. That depends on what we're mining the resource for. For example, if we're mining for metals to use in catalytic converters for vehicles, atom count is the relevant metric, since the catalytic effectiveness depends on the number of atoms, not on the total mass.
    - pdonis 8y ago
      > Iron is the "backbone" of our red blood cells No, it isn't; each hemoglobin molecule has just four iron atoms in it (IIRC--each heme structure has one, and I think there are four heme structures in one hemoglobin molecule). Most of each such molecule, by either mass or atom count, is carbon. And each red blood cell is more than just hemoglobin molecules.