WILLAMETTE

This historic iron meteorite, weighing 14,900 kg, was discovered by a Welsh immigrant named Ellis Hughes while prospecting for minerals. The location was 3 km northwest of Willamette, Clackamas County, Oregon, which is presently a part of West Linn. The iron mass was probably deposited in its current location by the largest floods ever scientifically documented, the Missoula Floods, which occurred at the end of the last Ice Age about 14,000 years ago. Willamette is a heavily weathered meteorite, possibly losing a fourth of its original weight through tens of thousands of years of terrestrial corrosion in the rainy Oregon valley. Over 8.5 kg of oxide–shale was present inside the pit, and nickel that was leached from the meteorite was found in the surrounding ground. The apex has lost 1–2 cm from its surface, and any fusion crust, regmaglypts, or flow structures that might have been present on the meteorite have since been removed.

Through long-term electrochemical action of dilute sulfuric acid, produced from the dissolution of troilite, an array of pits, holes, and deep cavities has been sculpted, while the material persisting between these cavities has taken the form of tapered, hourglass-shaped, pedestals (see bottom photo). When found, and probably upon entry, the bell-shaped mass was oriented with its blunt apex pointing into the ground, and the corroded, cavity-riddled, rear side directly level with the ground. Consequently, the cavities and pedestals are mostly aligned perpendicular to the rear side of the meteorite and the ground.

Because the meteorite was found situated on land belonging to the Oregon Iron and Steel Company, Mr. Hughes tried to purchase the portion of land on which it was located. However, after failing to acquire the necessary funds for the purchase, he and his 15-year-old son (as the story is told) prepared to secretly relocate the iron mass nearly 1.2 km to his own property. He first constructed a strong cart made of logs, with wheels fashioned out of tree stumps. Using a block and tackle, and utilizing his horse as a winch by walking it around a capstan from which a wire rope was attached to the meteorite, he slowly levered the huge iron mass high enough to overturn it onto the cart. He then used this rudimentary winching procedure over 40 times to pull the cart over soft ground and obstructions to his own property, amazingly taking only three months. Thereafter, Mr. Hughes charged visitors 25¢ admission to view his meteorite, until the day an attorney for the Oregon Iron and Steel Company noticed the cleared path leading back to their land.

Mr. Hughes was soon a defendant in Clackamas County Circuit Court, Case #7587. He based his defense on the fact that he rightfully found an abandoned Indian relic, previously revered by the Clackamas tribe as their Tomonowos, variously translated as "Heavenly Visitor" or "Visitor From the Moon". An Elder Wasco Indian testified that he had been told by the Clackamas Chief, Wochimo, that before battle, young warriors would dip their arrows into the sacred water that had collected in the basins of the meteorite. Other Indians testified that Native doctors of the Clackamas Tribe used the meteorite ceremonially in healing and purifying rituals. Songs and dances passed down from Tribal ancestors that were based on the Heavenly Visitor were also brought into evidence. Nevertheless, the jury found in favor of the Iron and Steel Company, and this verdict was upheld in the Oregon State Supreme Court ruling:

"Meteorites, though not embedded in the earth, are real estate, and consequently belong to the owner of the land on which they are found."

Following a short period on display at the Lewis and Clark Centennial Exposition in Portland, the meteorite was sold to a New York heiress, Elizabeth E. Dodge II, for $20,600, who then presented it to the American Museum of Natural History in New York in 1906. In 1935, the Hayden Planetarium was built around the Willamette and Cape York masses. In the late 1990's, amid publicity surrounding the construction of the Museum's Rose Center of Earth and Space, the Clackamas Tribe, now the Confederated Tribes of the Grand Ronde Community of Oregon, filed a claim under the Native American Graves Protection and Repatriation Act to have the meteorite returned to their lands in Oregon. A federal lawsuit was filed by the AMNH against the Grand Ronde, and the fate of the meteorite was finally settled out-of-court. An agreement was made recognizing the Tribes spiritual relationship with the meteorite, and ensuring an annual private visit to the meteorite by the Grand Ronde for religious, historical, and cultural purposes.

Willamette has a recrystallized texture with only remnant evidence of a medium Thomson (Widmanstätten) structure, the result of a significant impact-heating event. Following annealing, another lesser shock event produced Neumann bands with further annealing of kamacite. Shock-melted troilite nodules with spidery filaments, and monocrystalline schreibersite, occur throughout the meteorite. Structural evidence shows that the meteorite went through a molten stage on its parent body. Based on cooling rate models, the diameter of the parent body is estimated to have been ~100 km, taking ~50 m.y. for the core to solidify. Although trace-element studies suggests that the high-Ni trend of the IIIAB group may have been the source of the metal in the main-group pallasites, recent cooling rate data indicate otherwise (see the Imilac page).

The IIIAB iron group constitutes ~33% of all iron meteorites recovered. The 2.81 g partial slice of Willamette pictured above was sectioned from the 96.47 g mass shown below, which was purchased at the 2002 Macovich Auction in Tucson, Arizona. This mass was previously acquired for the Macovich Collection of Meteorites through a trade with the American Museum of Natural History in New York.

The 96.47 g section of Willamette from which the above specimen was removed.
Photo courtesy of The Macovich Collection of Meteorites.

The heavily corroded rear side of the Willamette meteorite.