Meteorite Care & Preservation
Yes, meteorites can and do rust. Most meteorites contain iron-nickel metal, and once that ancient alloy meets Earth's humid, oxygen-rich atmosphere, it begins a slow chemical reaction that can disfigure, weaken, and ultimately destroy a specimen if left unmanaged.
Written by Brian McDonald, IMCA #3323, Treasure Coast Meteorite Co.
Think you have a meteorite?
Meteorite Check
Free step-by-step screening
Check It Free →
Why Meteorites Rust on Earth
For most of their existence, meteorites have lived in an environment with no liquid water and almost no free oxygen. The iron-nickel metal locked inside them formed billions of years ago in the cores of differentiated asteroids, and it remained chemically stable in the vacuum of space throughout the long journey to Earth.
That stability ends the moment a meteorite lands. Earth's atmosphere contains roughly 21 percent oxygen, and most environments include enough water vapor to drive corrosion. When iron-nickel metal is exposed to oxygen and moisture, it reacts to form iron oxides and oxyhydroxides, the reddish-brown crust we recognize as rust.
Many meteorites also fall to Earth carrying tiny grains of a mineral called troilite (iron sulfide), and some contain trace chlorides absorbed from terrestrial groundwater or desert salts. Both of these compounds can dramatically accelerate corrosion, which is why some meteorites continue to deteriorate decades after they were recovered.
Which Meteorites Rust the Most?
Not every meteorite is equally vulnerable. The amount of metallic iron-nickel in a specimen is the single biggest factor determining how quickly it will rust.
Lawrencite Disease: The Chemistry of Meteorite Rust
Meteorite corrosion is not just ordinary rust. The classic, most destructive form is known among collectors as lawrencite disease, also called weeping meteorite disease. It is named for lawrencite, a naturally occurring iron-nickel chloride mineral (formula (Fe,Ni)Cl₂) that is found in trace amounts in many iron and stony-iron meteorites.
Lawrencite forms in the parent body and is stable in dry, oxygen-free space. On Earth, however, it is highly hygroscopic and reactive. As soon as a contaminated meteorite is exposed to humid air, the lawrencite begins to absorb water, hydrolyze, and release hydrochloric acid into the surrounding metal. The acid attacks the iron-nickel matrix, producing fresh iron chloride that then attacks more metal in a self-sustaining cycle that conservators sometimes call "active corrosion."
Researchers at institutions including the Smithsonian National Museum of Natural History and the Natural History Museum, London have documented this pathway extensively. The end product of the chain reaction is akaganeite, a hydrated iron oxyhydroxide chloride that appears as bright orange to reddish-brown crystals. Akaganeite is itself hygroscopic, so even after the original lawrencite is consumed, the corrosion continues to feed on atmospheric moisture.
Recognizing Lawrencite Disease
The visible symptoms are unmistakable. Affected specimens develop bright orange or red-brown spots that grow over time. In humid conditions, these spots ooze a yellow-green or reddish liquid, the phenomenon that gives "weeping meteorite disease" its name. The liquid is acidic and stains anything it touches. Untreated specimens eventually crack along the corroded zones, fragment, and in extreme cases reduce themselves to piles of orange powder.
Some meteorite varieties are notorious for it. Many Campo del Cielo, Odessa, and Sikhote-Alin irons can develop lawrencite disease if stored improperly, and pallasites such as Imilac and Esquel are especially vulnerable along the boundaries between olivine crystals and surrounding metal.
Even a meteorite that looks dry and stable can be deteriorating internally. Lawrencite-driven corrosion proceeds at relative humidity as low as 35 percent, well below the comfort range of most homes. Below roughly 30 percent the reaction effectively stops, which is why dry storage is the cornerstone of meteorite conservation.
Why Desert Meteorites Are Especially Prone to Rust
It seems counterintuitive that meteorites found in some of the driest places on Earth would be the most vulnerable to corrosion, but that is exactly what happens. Northwest African (NWA) finds, Saharan recoveries, and Australian Nullarbor specimens often arrive in collections already carrying significant chloride contamination.
The mechanism is simple. Even arid deserts experience occasional rain, dew, and rising groundwater. Over hundreds or thousands of years, salts from these brief moisture exposures soak into the porous rock and concentrate inside fractures, pores, and metal grain boundaries. When the meteorite is recovered and moved into a humid environment, those embedded chlorides reactivate.
By contrast, observed falls, meteorites recovered shortly after they were seen falling, are usually free of terrestrial contamination and tend to be far more stable in long-term storage. This is one reason collectors and institutions place a premium on documented falls.
How to Prevent Meteorite Rust
The good news is that meteorite corrosion can be slowed dramatically, and in many cases halted, with proper storage practices. The principles are the same ones used by major museum conservation labs.
Control humidity
The single most important factor is keeping relative humidity low and stable. A target of 30 percent or below will stop most chloride-driven corrosion. Silica gel desiccants in a sealed container offer an inexpensive starting point. Collectors with valuable specimens often invest in dry cabinets or sealed display cases with integrated humidity control.
Avoid temperature swings
Repeated cycles of warm and cool air drive moisture into and out of porous specimens. A closet on an interior wall is usually a better storage location than a basement, attic, or garage.
Handle minimally and clean hands
Skin contact deposits oils and chloride-rich sweat directly onto a specimen. When handling meteorites, use clean cotton or nitrile gloves and avoid touching freshly cut or polished surfaces.
Apply protective coatings selectively
Many serious collectors apply a thin coat of microcrystalline wax (such as Renaissance Wax) to iron meteorites. This creates a barrier against atmospheric moisture without significantly altering the appearance. Coatings should never be used to hide active corrosion. They must be applied to clean, dry, stable material.
Address active corrosion promptly
If you see orange weeping or rapid color changes, the specimen needs intervention. Conservators sometimes immerse affected meteorites in deionized water baths to leach out chlorides, or treat them with chemical stabilizers. These are specialized techniques. For valuable specimens, consult a meteorite conservator rather than attempting aggressive home treatment.
A meteorite that survived 4.5 billion years in space can be destroyed in a few decades by an open shelf in a humid room. Good storage is not optional, it is part of owning these objects.
Does Rust Affect Scientific Value?
Yes, and significantly. Rust obscures the original metal grains, mineral structures, and shock features that scientists use to classify and study meteorites. Heavily oxidized specimens may be reclassified as weathering grade W3, W4, or W5 on the standard Wlotzka scale used by the Meteoritical Society, with W6 indicating that all metal has been replaced by oxides.
This matters for collectors as well as researchers. A heavily weathered specimen is generally less desirable than a fresh one of the same classification, and severe corrosion can compromise structural integrity to the point that slices and end-cuts begin to crumble. Preservation, in other words, is also a question of value.
Related Questions
Browse Authentic Meteorites
Frequently Asked Questions
Do all meteorites rust?
No. Meteorites with little or no free metal, such as most lunar meteorites, Martian meteorites, and many achondrites, rarely show significant rust. Iron meteorites and ordinary chondrites are far more vulnerable because they contain metallic iron-nickel.
What is lawrencite disease?
Lawrencite disease, also called weeping meteorite disease, is a destructive form of corrosion caused by traces of the mineral lawrencite (iron-nickel chloride) inside iron and stony-iron meteorites. When exposed to humid air, lawrencite hydrolyzes to release hydrochloric acid, which attacks the surrounding metal in a self-sustaining cycle. The visible symptom is orange spots that ooze acidic liquid. Dry storage below 30 percent relative humidity is the standard treatment.
Why do iron meteorites rust so easily?
Iron meteorites are composed almost entirely of iron-nickel metal. With nothing to dilute or protect the metal, the entire specimen is essentially one large piece of corrodible material. Atmospheric oxygen and moisture attack it from every direction.
Can a rusting meteorite be saved?
Often, yes. Lowering the surrounding humidity will slow or halt most corrosion. For active chloride-driven weeping, conservators use deionized water rinses, chemical stabilization, and protective coatings. Valuable specimens should be evaluated by a meteorite conservator before any aggressive treatment.
Should I clean rust off my meteorite myself?
It depends on the specimen. Light surface rust on an iron can sometimes be carefully removed mechanically, but aggressive cleaning can damage fusion crust and original surface detail. When in doubt, document the specimen photographically before doing anything, and consult an experienced collector or conservator.
What humidity level is safe for meteorite storage?
A relative humidity of 30 percent or lower is the conservation standard for iron-bearing meteorites. Below 35 percent, chloride-driven corrosion essentially stops. Many collectors use sealed containers with silica gel to maintain these conditions inexpensively.
