Meteorites and Magnetite for Dummies

iron meteorite

We were a bit surprised when a staffer turned up today's DotD nominee, mainly because it didn't make a whole lot of sense. At a loss, we woke the staff geologist from his nap and asked him what he knew on the topic the kid found at Sciencing.com, "Magnetite Vs. Meteorite" [sic]. His comment? "About the only thing the two words have in common is that they both start with 'm' and end with 'ite.' Otherwise they're pretty much unrelated." Unfortunately, eHowian Cara Batema decided she could answer the question from the deep well of knowledge conferred by her BA in music therapy...

Just so you know the facts, which actually appear in one of Cara's references, magnetite – an iron oxide mineral – is exceedingly rate in meteorites.¹ There are plenty of meteorites that, like magnetite, are attracted to a magnet. That's because they are chunks and sometimes solidified droplets of nickel-iron, presumably from the core of a one-time planet. We guess that maybe the OQ wanted to know whether the specimen in hand was a meteorite or magnetite. To that end, Batema just wasn't much help. Here's her take on the question:

• "...meteorites, or pieces of asteroids or planets that fly through space and land on Earth, sometimes seem indistinguishable common terrestrial minerals like magnetite[sic]." – We might say they're mistaken for terrestrial minerals...
• "Both magnetite and meteorites have high levels of iron, which is one reason they are easily mistaken for each other." – Not all meteorites have "high levels of iron"; just the nickel-iron ones. Stony meteorites are far more common...
• "Most meteorites contain an iron and nickel alloy, while terrestrial rocks like magnetite most often do not contain nickel." – Not most, some. And you'd need to perform a chemical analysis to determine whether a sample contains nickel (as stated by Batema's reference)!
• "...magnetite has an isometric crystal form and its crystals are typically octahedrons or dodecahedrons (having 12 sides or faces), meteorites most often do not contain crystals." – Only a scientifically illiterate moron thinks every sample of magnetite consists of nice, clean crystals. Oh, and the plural of octahedron is octahedra.

• "Very few meteorites will not attract a magnet. A magnetite’s magnetism is considered weak, but it is strong enough to attract large nails." – Bullshit on both claims: only nickel-iron meteorites are attracted to a magnet (not the other way 'round, Cara); and the crap about "attract large nails" is just that: crap. Magnetite is attracted to magnets, not the other way around... again.
• "After years of exposure to the Earth’s atmosphere, [meteorites] to a rusty brown color. Magnetite remains a glossy black color unless it forms a yellow-brown rust from being washed or kept in a moist area." – Duh: the Earth's atmosphere is one such "moist area." Idjit.

Such are the hazards of asking a liberal arts major to explain science... you're likely to get the same sort of half-baked factoids and misinterpretation our Dumbass of the Day pounded out.

¹ Authoritative references point out, however, that the "fusion crust" on metallic meteorites, caused by a high-temperature passage through the atmosphere, often contains iron oxides, including magnetite. That's apparently where Batema cribbed her comments about streak.

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