Fragments of an iron meteorite scattered across 15 square kilometers record a cosmic impact around 500 years ago. Metallurgical analysis revealed Widmanstätten patterns indicating slow cooling in space.
A 500-year-old impact event
Roughly 500 years ago, a dense iron asteroid entered Earth's atmosphere over what is now central Myanmar. The intense heat and pressure of entry caused the meteoroid to fragment, resulting in a shower of metallic pieces. This event created the Wundwin strewn field, an area covering approximately 15 square kilometers where these extraterrestrial fragments landed.
A strewn field is the term for the debris pattern left by a mid-air meteorite fragmentation. As the object breaks apart, aerodynamic forces sort the pieces by size; smaller fragments lose momentum faster and land earlier along the flight path, while larger, heavier masses travel farther. The resulting debris field is typically elliptical, elongated in the direction of travel. The Wundwin field is an example of such an event, though the exact total known weight of all recovered fragments is not widely documented. The fragments themselves are composed primarily of an iron-nickel alloy that originated in the core of a much larger planetary body, likely an asteroid that was shattered billions of years ago.
Crystalline fingerprints from space
The scientific value of the Wundwin meteorite fragments lies in their internal structure. When pieces are cut, polished, and etched with a mild acid, a interlocking crystalline pattern emerges. This is the Widmanstätten pattern, a feature unique to certain iron meteorites and impossible to replicate on Earth. The pattern consists of interwoven bands of two different iron-nickel alloys: nickel-poor kamacite and nickel-rich taenite.
These crystals form only under conditions of extremely slow cooling—on the order of a few degrees Celsius per million years. This rate of cooling is only possible deep inside the metallic core of an asteroid or protoplanet, insulated by kilometers of rock. The width of the kamacite and taenite bands in the Widmanstätten pattern is directly related to the cooling rate and the meteorite's nickel content. Finer patterns generally indicate faster cooling, suggesting the parent body was smaller. Analysis of the Wundwin meteorite's structure shows the conditions inside the core of a planetary building block from the early solar system.
💡Fun Facts
The Widmanstätten pattern is named after Count Alois von Beckh Widmanstätten, who described the phenomenon in 1808 after noticing the patterns while flame-heating meteorite slabs.
Iron meteorites like those at Wundwin originate from the molten cores of differentiated asteroids that were destroyed by ancient impacts.
The crystalline structure is only visible to the naked eye after a slice of the meteorite is etched with an acid, as the two iron-nickel alloys (kamacite and taenite) react at different rates.
Iron meteorites make up only about 5% of observed meteorite falls, but they are found more often than stony meteorites because they are more resistant to weathering and easier to distinguish from Earth rocks.
The strewn field is an open, unfenced agricultural area and is accessible 24/7.
Admission
Free.
Accessibility
The area consists of rural, private agricultural land. Access is not formalized, and the terrain can be difficult. Finding fragments is extremely unlikely without expert knowledge and equipment.
The Wundwin Meteorite Strewn FieldMandalay Region, Myanmar