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It's (relatively) common knowledge that Mars is known as the "Red Planet" because of an abundance of iron oxide, AKA rust, on its surface. At first glance, that looks like "iron, iron, everywhere." But of course that's just the surface.

How common is iron in general on Mars? For example, if colonists wanted to produce iron, how long would it be before they'd have to start specifically digging mines to get at more? How easy would it be to refine iron from known surface substances on Mars, and how much iron you could reasonably expect to obtain thereby?

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  • $\begingroup$ What specifically is the question? Part of your question asks about Mars in general, and part about how abundant is iron specifically on its surface. That's two questions, and for the general part, distribution of iron would have to be discussed first. E.g. differences in geologic processes between the Earth and Mars, affecting surface, crust and mantle metal distribution, weaker Martian gravity slowing percolation rate of molten metals towards its (much smaller) core, and so on. Should we focus on surface and immediate subsurface abundance of iron ores instead? $\endgroup$ – TildalWave Aug 26 '15 at 20:30
  • $\begingroup$ @TildalWave: Yes, I'm mostly asking about surface and near-surface abundance of iron. A superficial examination makes it look like the whole place is made of iron oxide; I'm wondering how accurate that perception is, since it obviously can't be the whole planet made of one substance through-and-through. $\endgroup$ – Mason Wheeler Aug 26 '15 at 20:35
  • $\begingroup$ If I'm not mistaken, you're asking how easy it would be to refine iron from known surface substances on Mars, and how much iron you could reasonably expect to obtain thereby. $\endgroup$ – Jerard Puckett Aug 27 '15 at 3:52
  • $\begingroup$ What else do you expect? Iron is very common for nuclear reasons: it cannot be fused nor fissioned. Stars go supernova when their cores are all iron. Iron is a metal that will react with a lot: oxygen, halogens, sulphur, etc, but it all strips off fairly easy. $\endgroup$ – MSalters Aug 28 '15 at 15:03
  • $\begingroup$ There is zero iron on the surface, since a surface is a two-dimensional object. There is lots of iron below that surface, all the way to the core. $\endgroup$ – Mark Adler May 21 '18 at 6:03
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Martian meteorites suggest that the Martian crust has about twice as much iron as the earth's crust. Of course Mars is smaller than Earth, but most of Earth is covered in water. As a result, Mars has more available iron.

Concentration is another matter, as Earth's water tends to collect iron in deposits. Still, Mars has hematite and olivine ores - it had water when it was young. And you might even vacuum up all that red dust. Even more convenient, the mafic (iron rich) dust has a smaller grain size than the felsic (iron poor) dust. Magnets and a sieve are enough to get iron-enriched dust.

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  • $\begingroup$ Martian dust seems to contain only 2% by weight iron oxide. I suppose that the dust and sand dunes would be most accessible. Was Mars geologically active long enough to create interesting ore deposits? The best place on Mars for resource X can be very good. Gold nuggets used to lie around on Earth before we picked them up. $\endgroup$ – LocalFluff Aug 28 '15 at 16:27

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