I'm building a project featuring several very exotic alien worlds, one of which I had a question about the blood of aliens since the amount of Metals like iron are scarce, so I opted for something else, silicon, is that possible!? What color would this be when oxygenated and deoxygenated? Would this be efficient enough to sustain a complex organism?

  • $\begingroup$ The good news is that organosilicon chemistry is a real thing. The bad news is that there is no example of an organosiliconic respiratory pigment... The best news is that we have real-life practical evidence that non-organometallic perfluorocarbon-based blood is actually possible. $\endgroup$
    – AlexP
    Commented Dec 14, 2023 at 2:22
  • $\begingroup$ Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. $\endgroup$
    – Community Bot
    Commented Dec 14, 2023 at 3:21
  • $\begingroup$ Why are you proposing silicon? Am I correct in understanding that your project is to get rid of the iron in our blood and replace it with silicon? Those two elements have different electronic configurations, their chemistry have very little in common, oxidation states in particular are different (the fact that one of them is a metal and the other a semiconductor should alert you that this does not sound like a wise replacement to make) $\endgroup$ Commented Dec 14, 2023 at 10:01
  • $\begingroup$ As I understand the question, it is "Could a complex life-form evolve with silicon-based blood instead of iron-based?" $\endgroup$
    – FlaStorm32
    Commented Dec 14, 2023 at 18:04

1 Answer 1


Lots of people have thought of this and discounted it as extremely unlikely.

Bonding to carbon is the main problem. But there was a French study that thinks it's possible. So taking that as a basis then theoretically you could have silicon based life. But it's doubtful with our current knowledge that such life could become complex in the way we have on earth, let alone intelligent. So it's probably not going to have blood at all.

If it did evolve complex lifeforms there is no way of telling what it would look like let alone it's blood colour.

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    $\begingroup$ I don't think this answers OP's question. As far as I can tell, he only discusses the possibility of replacing the iron in our blood with silicon (I don't see how that would make sense, but that's what I read). The study you're referencing discusses the possibility of introducing some silicon in carbon chains, which is another problem. The article is behind a paywall, but from the abstract, it doesn't seem they adress at all oxygen capture via silicon complexes, which should be OP's main concern when getting rid of iron $\endgroup$ Commented Dec 14, 2023 at 9:50

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