Kaalijarv Iron Meteorite Slice, IAB-MG, 28.43g, Etched Widmanstatten Pattern

Etched slice with crossing kamacite plates

This 28.43 g slice of Kaalijarv is etched on both faces. Gray kamacite plates cross one another at angles across the main face, with a few brighter plates standing out, the etched pattern known as the Widmanstatten structure.

Kaalijarv is the iron recovered from the Kaali crater field on Saaremaa, Estonia. The Meteoritical Bulletin records it as a find, recovered in 1937, and classifies it as Iron, IAB-MG.

Structure and features

The plates run in several directions and meet at angles, many of them close to right angles, the structure the octahedrite label describes. The close-up photographs show bright and darker gray plates side by side, separated by narrow seams. The second face carries a fainter version of the same pattern.

The specimen was stabilized by Brian McDonald of Treasure Coast Meteorite Co. and given a thin coat of lacquer. The display stand and scale cube in the photographs are not included.

Scientific context

The Meteoritical Bulletin classifies Kaalijarv as Iron, IAB-MG. MG stands for main group: Kaalijarv belongs to the main group of the IAB complex, a grouping assigned from trace element composition and nickel content rather than from etched structure (Wasson and Kallemeyn, 2002, The IAB iron-meteorite complex, Geochimica et Cosmochimica Acta, volume 66). The Meteoritical Bulletin classification note sets out the definition.

IAB irons differ from the magmatic iron groups that are thought to have crystallized in the cores of melted asteroids. Many IAB irons carry silicate inclusions and show wider chemical variation, and Wasson and Kallemeyn (2002) argue that the group formed mainly by crystal segregation in rapidly cooling melts produced by impacts, rather than by slow cooling in a planetary core.

For background on how meteorites are classified, see Learn About Meteorites.

The story

The Kaalijarv impact happened on an island where people already lived. Its largest crater, now a round lake, sits in the village of Kaali on Saaremaa, Estonia’s largest island, with eight smaller craters around it. Research dates the impact to the Bronze Age, and the team that produced the most precise date concluded that it was probably witnessed by the people of Saaremaa.

What those people made of it has fascinated Estonians for decades. The best-known answer comes from Lennart Meri, the writer and ethnographer who later served as President of Estonia. In his 1976 book Hõbevalge (published in English in 2025 as Silverwhite: The Journey to the Fallen Sun), Meri argued that memories of the impact survive in the old folk poetry of Estonians and Finns, including passages in the Kalevala describing fire falling from the sky, and that Saaremaa itself might be the Ultima Thule described by the ancient Greek explorer Pytheas.

These ideas are a hypothesis, not an established finding, and much of Meri’s wider reconstruction of early Baltic history has not held up to later research. The possible echoes of the impact in regional folklore continue to be discussed by folklorists.

Sources: Losiak et al. (2016), cited below; Lennart Meri, Hõbevalge (1976); article on echoes of the Kaali impact in Folklore: Electronic Journal of Folklore, volume 23.

What the research reports

The Meteoritical Bulletin lists this meteorite as Kaalijarv, classified Iron, IAB-MG, a main group member of the IAB complex, found in 1937 in Estonia with a recorded mass of 2.25 kg. The entry notes that Kaalijarv was never published in the Meteoritical Bulletin itself; its classification comes from the Natural History Museum Catalogue of Meteorites (2000) and MetBase (2006). The crater field is listed separately in the Bulletin as Kaalijärv. The research below concerns when the craters formed, and its findings come from the authors’ own fieldwork and dating.

Losiak et al. (2016): dating the impact

A. Losiak, E. M. Wild, W. D. Geppert, M. S. Huber, A. Jõeleht, A. Kriiska and colleagues published Dating a small impact crater: An age of Kaali crater (Estonia) based on charcoal emplaced within proximal ejecta (Meteoritics & Planetary Science, volume 51, 2016). Earlier estimates of the crater’s age had varied by as much as 6,000 years, from about 6400 BCE to about 400 BCE. By radiocarbon dating charred plant material caught in the debris thrown out of the crater, which ties the sample directly to the impact, the team concluded that the crater most probably formed shortly after 1530 to 1450 BCE. Because Saaremaa was already inhabited, they write, the event “was probably witnessed by humans.”

Why this listing calls Kaalijarv an octahedrite

The Meteoritical Bulletin Database records iron meteorites by chemical group, so its entry for Kaalijarv reads Iron, IAB-MG, with no structural class. That reflects how the database is organised rather than anything about Kaalijarv itself. A 2022 review of meteorite classification, Meteorite petrology versus genetics: Toward a unified binominal classification, notes that the database recognises only the iron class at the top level, and that for many irons “structural classes can be extracted from Buchwald’s (1975) compilation.”

The Kaalijarv entry links directly to that compilation: Vagn F. Buchwald’s Handbook of Iron Meteorites (University of California Press, 1975), volume 2, pages 704 to 707. Buchwald describes Kaalijarv as a coarse octahedrite, as summarised by the reference Wiki.Meteoritica.pl, which cites those pages. The Widmanstätten structure visible when a Kaalijarv slice is etched is the feature that term describes. This listing uses “octahedrite” on that basis, and notes here that the term comes from Buchwald rather than from the Bulletin entry.

Frequently asked questions

Is this meteorite authenticated?
Kaalijarv is classified in the Meteoritical Bulletin Database as Iron, IAB-MG, and the entry is linked at the end of this listing. Treasure Coast Meteorite Co. is IMCA member #3323. This specimen includes a certificate of authenticity documenting its weight, classification, and provenance.

Is Kaalijarv a fall or a find?
The Meteoritical Bulletin records Kaalijarv as a find, recovered in 1937. The craters formed in the Bronze Age, and Losiak et al. (2016) conclude the impact was probably witnessed, but no fall was observed and recorded, so the official status is find.

What is included with this specimen?
The 28.43 g slice as photographed and a certificate of authenticity. Display stands and scale cubes shown in the photographs are not included.

How should I store an etched iron meteorite?
Keep it in a low-humidity environment. Etched surfaces react to moisture more readily than natural surfaces, so a silica gel pack in the storage container helps prevent oxidation. This specimen carries a thin lacquer coat, so no oil is needed.

Collector significance

This 28.43 g slice pairs a clear etched structure with a documented origin: a crater field on Saaremaa dated by Losiak et al. (2016) to shortly after 1530 to 1450 BCE, on an island that was already inhabited. The crossing plate pattern covers the whole of the main etched face, with a few bright plates that stand out from the gray.

For more iron meteorites, see our full Iron Meteorites collection.

Meteoritical Bulletin entry: Kaalijarv | Classification: Iron, IAB-MG | Find, Estonia, 1937 | Treasure Coast Meteorite Co., IMCA #3323