Most meteorites will attract a magnet, but they are far from equally magnetic, and a small number barely respond at all. The iron-nickel metal scattered through the majority of space rocks is what makes them stick to a refrigerator magnet in the first place, yet the amount of that metal varies enormously depending on the type of meteorite, how long it has sat on Earth’s surface, and what happened to it in space before it fell. Understanding why some meteorites practically leap onto a magnet while others produce only a feeble tug matters both for identifying a suspicious rock and for the science locked inside it.
Where the Magnetism Comes From
The magnetism in most meteorites traces to grains of iron-nickel alloy, primarily a mineral called kamacite. Kamacite is strongly ferromagnetic, meaning it responds vigorously to an external magnetic field and can hold its own permanent magnetization. In ordinary chondrites, which make up the bulk of meteorite falls witnessed by people, kamacite is the dominant magnetic mineral, accounting for the vast majority of their total magnetic signal.1Uchenye Zapiski Kazanskogo Universiteta Seriya Estestvennye Nauki. The effect of terrestrial weathering on the magnetic properties of meteorites from the Atacama Desert Iron meteorites, which are essentially solid masses of iron-nickel alloy, are the most magnetic of all. Stony-iron meteorites, a rarer class containing roughly equal parts metal and silicate rock, fall somewhere in between.
Other minerals contribute too. Magnetite, the same iron oxide that makes lodestone magnetic on Earth, shows up in surprising abundance in certain meteorite types. And an unusual ordered form of iron-nickel called tetrataenite has been found in some chondrites, where it produces an extremely stable magnetization that resists being erased by ordinary alternating magnetic fields.2Journal of Geophysical Research: Solid Earth. High magnetic coercivity of meteorites containing the ordered FeNi (Tetrataenite) as the major ferromagnetic constituent Tetrataenite forms over millions of years of extremely slow cooling, a timescale impossible to replicate in a laboratory, and it clings to its magnetization so stubbornly that even heating to several hundred degrees Celsius does not erase it. Only when the temperature climbs high enough to disorder the crystal structure does the effect disappear.
How Magnetic Strength Varies by Meteorite Type
If you lined up representatives of every major meteorite class and tested them with a magnet, you would see a wide spectrum. Iron meteorites sit at one extreme. A hand magnet snaps onto them with obvious force. Ordinary chondrites, the most common stony meteorites, are also recognizably magnetic, though less so. Within the ordinary chondrites there is a predictable gradient: H chondrites (“high iron”) contain the most metal and are the most magnetic, L chondrites (“low iron”) less so, and LL chondrites (“low iron, low metal”) are the weakest of the three. This relationship is so consistent that a quick magnetic susceptibility measurement can sort an ordinary chondrite into its proper class without cutting or grinding the sample.3Meteoritics & Planetary Science. Magnetic classification of stony meteorites: 1. Ordinary chondrites
Achondrites, the stony meteorites that formed from melted or partially melted parent bodies, tell a messier story. Because melting and differentiation can separate metal from rock, some achondrites ended up with very little iron-nickel metal. As a group, achondrites are much more variable in metal content than chondrites, both from one meteorite to the next and across entire parent bodies.4Meteoritics & Planetary Science. Magnetic classification of stony meteorites: 3. Achondrites Ureilites, a carbon-rich achondrite group, are an exception: they tend to be more consistently metallic and therefore more magnetic. But aubrites, which are essentially iron-free silicate rocks from a differentiated body, are among the least magnetic meteorites you will encounter. A fridge magnet held against an aubrite would provoke almost no response.
Meteorites That Barely Register on a Magnet
Martian meteorites illustrate the low end of the spectrum well. Samples from seven different Martian meteorites have been studied magnetically, and all of them carry only a weak natural magnetization. The magnetic signal comes from tiny amounts of titanomagnetite, generally less than one percent of the rock’s mass.5Meteoritics & Planetary Science. Magnetic properties of Martian meteorites: Implications for an ancient Martian magnetic field You could hold a magnet next to one of these rocks and feel nothing. The magnetization they do carry is interesting because it records the ancient Martian magnetic field, not because it makes the rock behave like a piece of iron.
Lunar meteorites are similarly feeble. The Moon has no global magnetic field today and only had weak, patchy fields early in its history, so lunar rocks contain minimal ferromagnetic material. Some achondrites from other parent bodies also fall into this barely-magnetic category, particularly those that went through extensive melting that stripped metal away from silicate rock. For a casual rock hunter, this means that passing a magnet over a stone and getting no pull does not automatically rule out a meteorite, it just rules out the most common types.
Carbonaceous Chondrites and Magnetite
Carbonaceous chondrites occupy a curious middle ground. Many of them are not especially rich in iron-nickel metal, yet they contain abundant magnetite formed through a completely different process: water-rock reactions on their parent asteroids. When liquid water percolated through the rock billions of years ago, it chemically altered iron-bearing minerals and produced magnetite as one of the main byproducts. In some carbonaceous chondrites, magnetite makes up as much as ten percent of the rock by weight, and in certain samples of the Tagish Lake meteorite it reaches around seventeen percent.6Meteoritics & Planetary Science. Unusual forms of magnetite in the Orgueil carbonaceous chondrite
This magnetite shows up in a striking variety of crystal shapes, from tiny spheres and framboids to platelets and irregular masses. The morphology of these grains provides a timeline of the conditions inside the parent asteroid during alteration, so researchers study them closely. From a practical standpoint, carbonaceous chondrites often respond to a magnet, but the pull feels different from that of an ordinary chondrite because the magnetic mineral is magnetite rather than metallic iron-nickel. Magnetite is ferromagnetic but significantly weaker per unit mass than kamacite, so a carbonaceous chondrite with ten percent magnetite may feel roughly comparable to an ordinary chondrite with a much smaller percentage of metal.
What Happens to Magnetism After a Meteorite Lands
A meteorite sitting on Earth’s surface is not magnetically frozen in time. Terrestrial weathering attacks the iron-nickel metal, converting it to rust-like minerals, and this progressively weakens the rock’s magnetic response. Studies of ordinary chondrites recovered from the Atacama Desert, where meteorites can survive for tens of thousands of years, show a clear pattern: as the weathering grade increases, the total magnetic signal drops. In H chondrites, the decline tracks closely with what you would expect if kamacite were converting into weakly magnetic or non-magnetic minerals like akaganeite. Early weathering stages hit metal first, faster than they attack the sulfide mineral troilite. Only in more advanced weathering stages do small amounts of new magnetite or maghemite appear.1Uchenye Zapiski Kazanskogo Universiteta Seriya Estestvennye Nauki. The effect of terrestrial weathering on the magnetic properties of meteorites from the Atacama Desert
This matters for anyone trying to classify a meteorite using a quick magnet test. A freshly fallen meteorite will have its full complement of metal and a strong magnetic pull. A meteorite that has been lying in a desert or a field for centuries may have lost a significant fraction of that metal to oxidation. The same classification tool that works beautifully on witnessed falls or well-preserved samples becomes less reliable for heavily weathered finds, because the magnetic susceptibility reading is now reflecting both the original metal content and the degree of rust.7PubMed Central. Data-driven classification of ordinary chondrites and asteroidal metal potential evaluation A weathered L chondrite might look magnetically like an LL chondrite, leading to misclassification.
The Fusion Crust Complication
When a meteoroid tears through Earth’s atmosphere, friction heats its surface to thousands of degrees and melts a thin outer shell. This melt solidifies into the dark, glassy coating known as a fusion crust. The process is violent enough to change the magnetic properties of that outer layer. In the Allende carbonaceous chondrite, researchers found that the outer millimeter had been remagnetized as the fusion crust cooled in Earth’s magnetic field, overwriting whatever ancient signal had been there.8Earth and Planetary Science Letters. Natural remanent magnetization and thermomagnetic properties of the Allende meteorite
The chemistry of the fusion crust itself is also different from the interior. In the Ozerki L6 meteorite, for example, the fusion crust showed a decreased saturation magnetic moment compared to the interior because some of the iron-nickel-cobalt alloy was destroyed during melting, replaced in part by magnesioferrite, a different iron-bearing mineral.9Meteoritics & Planetary Science. Characterization of the matrix and fusion crust of the recent meteorite fall Ozerki L6 So the outermost skin of a meteorite is magnetically distinct from its interior: slightly weaker in raw magnetic pull and carrying a magnetization acquired during the last few seconds of flight rather than billions of years ago in space.
Shock and What It Does to Magnetic Memory
Long before atmospheric entry, most meteorites experienced violent collisions in space. Impacts between asteroids subject rocks to shock pressures that can reach tens or even hundreds of gigapascals, and those pressures rearrange magnetic minerals at the grain level. Shock experiments on pyrrhotite, a common magnetic sulfide in meteorites, showed that high-field magnetization could be reduced by up to ninety percent, primarily by wiping out the weaker components of the magnetic signal. At the same time, the surviving grains became magnetically harder, meaning they held onto their remaining magnetization more stubbornly.10Geophysical Research Letters. Effect of shock on the magnetic properties of pyrrhotite, the Martian crust, and meteorites
In iron meteorites the story is similar but with an extra twist. Experiments on the Chinga iron meteorite subjected to pressures exceeding a hundred gigapascals showed that the magnetic hardness stayed roughly the same in the outer zones of the sample, where temperatures remained moderate. But in the center, where temperatures climbed above the threshold for tetrataenite to disorder into ordinary taenite, the magnetic hardness dropped sharply.11Springer International Publishing. The Effect of 30 to >100 GPa Shock on the Magnetic Properties of Chinga Iron Meteorite Shock does not necessarily make a meteorite non-magnetic, but it scrambles the ancient magnetization record that scientists want to read. And in some cases, the post-impact cooling itself can imprint a new magnetization, even one acquired in the absence of an external field, simply from the internal stresses and domain rearrangements the shock produced.12The Moon. The magnetic effects of brecciation and shock in meteorites. I – The LL-chondrites
Why You Should Never Touch a Meteorite with a Strong Magnet
Here is where the question of magnetism intersects with a real-world warning. Collectors, dealers, and even some museum visitors routinely press strong magnets against meteorites to confirm their identity. That quick test can irreversibly destroy billions of years of scientific data. Touching a meteorite with a hand magnet results in near-instantaneous destruction of its ancient magnetic record.13Journal of Geophysical Research: Planets. Hand Magnets and the Destruction of Ancient Meteorite Magnetism The magnet does not just add a new magnetization on top of the old one; it overwhelms and replaces the original signal, permanently. Researchers demonstrated this effect on the oldest known Martian meteorite, the Northwest Africa 7034 pairing group, and found that after magnet exposure the paleomagnetic information was gone.
If you find a rock you suspect is a meteorite, the responsible approach is to use a weak magnet held a short distance away, or better yet, to check whether the rock attracts a compass needle. That gives you the same diagnostic information without overwriting the magnetic record that planetary scientists might later want to study. A neodymium magnet dragged across the surface is the single worst thing you can do to a meteorite’s scientific value short of throwing it in a furnace.
What Ancient Magnetism in Meteorites Tells Us About the Early Solar System
The reason researchers care so much about preserving meteorite magnetism is that these rocks are time capsules of magnetic fields that existed when the solar system was forming. The gas and dust disk that surrounded the young Sun was threaded with magnetic fields, and those fields played a central role in how matter moved inward toward the Sun and how planets eventually assembled. Meteorites that cooled and solidified while that disk was still present locked in a snapshot of the local field strength.
Paleomagnetic measurements of meteorites have revealed fields of roughly 0.5 gauss at distances of about one to three astronomical units from the Sun, present until at least 1.2 million years after the solar system began forming. Farther out, at three to seven astronomical units, the field was weaker but still detectable until at least 2.5 million years.14PubMed Central. History of the solar nebula from meteorite paleomagnetism These intensities are consistent with the field strengths needed to drive the rates of gas accretion that astronomers observe around other young stars, which suggests that magnetism was a primary engine of disk evolution.
One of the most striking recent findings comes from the andesite meteorite Erg Chech 002, which contains submicron iron grains that act as extremely reliable magnetic recorders. Analysis of this meteorite indicates it recorded a field of about 60 microtesla at a distance of roughly two to three astronomical units from the Sun, about two million years after the formation of the oldest known solar system solids.15PubMed Central. A 4,565-My-old record of the solar nebula field That field can only be explained by the solar nebula itself, not by the meteorite’s small parent body.
By contrast, volcanic angrites that formed about 3.8 million years after the solar system’s beginning show essentially zero magnetic field, less than 0.6 microtesla.16PubMed. Lifetime of the solar nebula constrained by meteorite paleomagnetism The implication is stark: the nebular gas, and the magnetic field it carried, had dispersed by that point. Meteorites are the only way to reconstruct this timeline with any precision, because no telescope can observe a disk that vanished 4.5 billion years ago. Every time someone drags a magnet across a newly found meteorite, a potential data point for this kind of research disappears.
Magnetism on Asteroid Parent Bodies
Some meteorites carry magnetic signatures that point not to the solar nebula but to magnetic fields generated within their own parent asteroids. The howardite-eucrite-diogenite (HED) meteorites, widely thought to originate from the asteroid Vesta, carry primary magnetizations that researchers have tentatively attributed to an internally generated field. The idea is that Vesta, after differentiating into a metallic core and silicate mantle, may have briefly sustained a small dynamo, somewhat like Earth’s core dynamo but on a much smaller and shorter-lived scale. As the asteroid’s outer layers cooled, they locked in this internal field.17Earth and Planetary Science Letters. Magnetic properties of howardite, eucrite and diogenite (HED) meteorites: Ancient magnetizing fields and meteorite evolution
Whether tiny asteroids could genuinely power dynamos remains an active area of research. The evidence from HED meteorites is suggestive but not conclusive, partly because shock and later thermal events can overprint or mimic a dynamo signal. Mars clearly had a global magnetic field early in its history, as recorded by the weak but stable magnetizations in Martian meteorites, though that field had died by the time the youngest Martian meteorites formed. Understanding which parent bodies had dynamos, and for how long, feeds directly into models of how quickly small bodies heat up, differentiate, and cool, questions that matter for understanding the building blocks of planets.
Practical Identification Without Damaging the Rock
For someone who has found a rock and wants to know if it is a meteorite, magnetism remains the single quickest screening test. Virtually all iron meteorites, stony-irons, and ordinary chondrites will attract a standard refrigerator magnet or a small neodymium magnet suspended on a string. If the rock pulls the magnet noticeably, that passes the first filter. The catch is that plenty of terrestrial rocks also contain magnetite or other magnetic minerals. Basalt, some types of industrial slag, and magnetite-bearing sandstone can all fool a magnet test. So magnetism is necessary but not sufficient for most meteorite types.
For the less common meteorite types, the test is less reliable. A carbonaceous chondrite might give only a modest pull. An aubrite or a lunar meteorite might give almost none. If you suspect you have one of these rarer types, visual clues like a fusion crust, chondrules visible on a cut surface, or an unusually high density relative to common rocks become more important than the magnet test alone. And regardless of how you test, keep strong magnets away from the surface. A compass needle deflected from a few centimeters away provides the same yes-or-no answer without risking the rock’s paleomagnetic record.