Kaalijärv Iron Meteorite Slice, IAB-MG, 33.00g, Widmanstätten Pattern

Bronze Age impact iron from Estonia's crater field

This 33.00g slice originates from the Kaali crater field on Saaremaa Island, Estonia, where a meteorite fragmented during atmospheric entry and impacted approximately 3,500 years ago during the Bronze Age. The Kaalijärv meteorite is one of the few iron meteorites directly linked to a preserved terrestrial impact structure with documented human settlement in the vicinity at the time of fall. Acid etching reveals the internal crystalline architecture formed during slow cooling in the metallic core of a differentiated asteroid.

The slice shows kamacite and taenite bands intersecting across the polished and etched surface. The boundaries between crystal phases are sharp and well-defined, characteristic of IAB-MG octahedrites that crystallized over millions of years in a parent body shielded from rapid temperature change. Surface preparation brings out contrast between the metallic phases without obscuring structural detail.

Kamacite-taenite intergrowth and octahedrite structure

The Widmanstätten pattern visible on this specimen consists of kamacite plates nucleating along specific crystallographic planes within a taenite matrix. This structure forms exclusively in metallic bodies cooling at rates between 1 and 100 degrees Celsius per million years. Faster or slower cooling produces different iron meteorite subtypes with distinct internal geometries.

IAB-MG meteorites show medium to coarse bandwidth in their kamacite lamellae, typically ranging from 0.5 to 3.0 millimeters. The etched surface on this slice displays this banding clearly, with individual kamacite plates extending across the face without significant distortion. The metallic luster remains intact along unetched regions, providing visual contrast between structural and reflective surfaces.

Scientific context of IAB complex irons

The IAB complex represents a diverse group of iron meteorites with silicate inclusions and compositional variations that suggest formation in a parent body that underwent partial differentiation followed by catastrophic disruption and reassembly. Unlike fully differentiated iron meteorite groups that formed in stable planetary cores, IAB meteorites likely originated from a rubble-pile asteroid containing both metallic and silicate material mixed during post-impact reassembly.

The MG (medium to coarse octahedrite) structural classification indicates cooling rates consistent with burial depths of tens of kilometers within the parent body. Material from Kaalijärv provides physical evidence of these processes and offers collectors a specimen type formed under conditions no longer occurring in the present-day solar system. For foundational information on meteorite formation and classification, see our Learn About Meteorites guide.

Frequently asked questions

Is this meteorite authenticated? Yes. Kaalijärv is classified as an IAB-MG octahedrite in the Meteoritical Bulletin. You can verify the classification through the Meteoritical Bulletin Database. This specimen includes a certificate of authenticity from Treasure Coast Meteorite Co.

What does IAB-MG mean? IAB refers to the chemical and isotopic group, indicating this meteorite belongs to the IAB complex of iron meteorites. MG designates the structural class as a medium to coarse octahedrite, based on kamacite bandwidth visible after etching. This classification reflects both composition and cooling history.

What is included with this specimen? You receive the 33.00g etched slice and a certificate of authenticity. No display stand is included unless otherwise stated.

Why is Kaalijärv historically significant? The Kaali impact occurred during the Bronze Age when the region was inhabited. The crater field is one of the few meteorite impact sites with a confirmed fall date within the span of recorded human activity, making material from this locality relevant to both planetary science and archaeoastronomy.

Display and collection value

Kaalijärv occupies a distinct position among iron meteorites due to its association with a documented impact crater and a fall event contemporaneous with human settlement. Material from this locality is finite, and etched slices that display clear Widmanstätten structure are sought by collectors interested in impact geology and historically significant meteorites.

This specimen weighs 33.00g, a size suitable for detailed examination of crystalline structure while remaining practical for display in standard meteorite cases or shadow boxes. The etched surface provides educational value for those studying metallic meteorite formation and cooling processes. Additional examples of octahedrites and other iron meteorite subtypes are available in our Iron Meteorites collection.

Meteoritical Bulletin entry: Kaalijarv | Classification: Iron meteorite (IAB-MG octahedrite) | Find, Estonia, 1937