A remarkable discovery has turned a long-standing barn doorstop on a Michigan farm into a scientifically recognized extraterrestrial artifact. The 10.22-kilogram rock, which had been used for decades to prop open a door, has now been identified as a new IIIAB iron meteorite.
The story of the Edmore meteorite began in 1939 when it was reportedly seen falling near Edmore, Michigan. Instead of being immediately studied, the unique specimen became part of daily farm life, eventually serving its mundane role as a doorstop. Even as the farm changed hands over the years, the unusual rock and its origin story were passed down to new owners.
A 2018 Event Sparks Curiosity
The true nature of the rock came under serious scrutiny after another meteorite fell near Hamburg, Michigan, in January 2018. This event prompted the current owners of the Edmore farm to reconsider the inherited doorstop, wondering if their peculiar rock could also be a meteorite.
They subsequently took the specimen to Central Michigan University in Mt. Pleasant for examination. Scientists at the university, collaborating with the Smithsonian Institution, embarked on a detailed analysis.
Uncovering Meteoritic Clues
The roughly triangular specimen measures approximately 17 x 20 x 23 centimeters. Its exterior features several large indentations and parts covered by a light-brown fusion crust—a thin layer formed when a meteoroid's outer surface melts and rapidly cools during its high-speed passage through Earth's atmosphere.
Initial tests confirmed characteristics consistent with an iron meteorite, leading scientists to send a slice of the rock to the Smithsonian Institution for more advanced analysis. Researchers used a Nova NanoSEM 600 scanning electron microscope and energy-dispersive X-ray spectroscopy.
Revealing Internal Structure and Origin
Treatment of the polished slice with Nital and alcohol revealed a distinct Widmanstätten pattern—a unique crystalline structure found in iron meteorites. This pattern is evidence of extremely slow cooling over vast periods within a parent body in space.
The structure indicated that the Edmore specimen was a medium octahedrite, composed of kamacite, taenite, and schreibersite. Kamacite lamellae were found to be about 0.8 millimeters wide, while schreibersite grains reached up to 4 millimeters and exhibited extensive fracturing. Chemical analysis, including iridium data, further classified the Edmore meteorite into the IIIAB group of iron meteorites.
In 2019, the specimen was officially recognized and listed in the Meteoritical Bulletin as “Edmore, Michigan, an Iron, IIIAB meteorite.” This confirmation transformed a decades-old farm artifact into a significant scientific discovery, finally acknowledging its extraterrestrial journey.