Iron, Modifying term used to describe meteorites that are mineralogically and/or chemically unique and defy classification into the group or sub-group they most closely resemble. Some examples include Ungrouped Achondrite (achondrite-ung), Ungrouped Chondrite (chondrite-ung), Ungrouped Iron (iron-ung), and Ungrouped Carbonaceous (C-ung). Click on Term to Read More, recrystallized Most Common type of iron meteorite, composed mainly of taenite and kamacite and named for the octahedral (eight-sided) shape of the kamacite crystals. When sliced, polished and etched with an acid such as nitric acid, they display a characteristic Widmanstätten pattern. Spaces between larger kamacite and taenite plates are often Click on Term to Read More
45° 22′ N., 122° 35′ W. This historic Meteorite composed mainly of iron (Fe) and nickel (Ni) in the form of two alloys, kamacite and taenite. Due to their metallic makeup and extraordinary weight, iron meteorites are easily distinguished from ordinary rocks. Also, because they rarely break up in the air and suffer much less from the effects Click on Term to Read More, 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 at its Meteorite not seen to fall, but recovered at some later date. For example, many finds from Antarctica fell 10,000 to 700,000 years ago. Click on Term to Read More 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 Work in progress. A solid natural object reaching a planet’s surface from interplanetary space. Solid portion of a meteoroid that survives its fall to Earth, or some other body. Meteorites are classified as stony meteorites, iron meteorites, and stony-iron meteorites. These groups are further divided according to their mineralogy and Click on Term to Read More, 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 Melted exterior of a meteorite that forms when it passes through Earth’s atmosphere. Friction with the air will raise a meteorite’s surface temperature upwards of 4800 K (8180 °F) and will melt (ablate) the surface minerals and flow backwards over the surface as shown in the Lafayette meteorite photograph below. Click on Term to Read More, regmaglypts, or flow structures that might have been present on the meteorite have since been removed.
‘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. Although Willamette shows compositional similarities to members of both the IIIAB and IIIE groups, Rubin et al. (2015) observed significant differences in inclusions from these iron groups; therefore, they suggest the reclassification of Willamette as an ungrouped iron. The meteorite exhibits a recrystallized texture with only remnant evidence of a medium Thomson (Widmanstätten) structure, the result of a significant impact-heating event. Following an extended period of annealing, another lesser shock event produced Neumann bands and further annealing of More common than taenite, both taenite and kamacite are Ni-Fe alloys found in iron meteorites. Kamacite, α-(Fe,Ni), contains 4-7.5 wt% Ni, and forms large body-centered cubic crystals that appear like broad bands or beam-like structures on the etched surface of a meteorite; its name is derived from the Greek word Click on Term to Read More at depth. Troilite nodules exhibit features of crushing and limited shock-melting, while monocrystalline Ni-Fe phosphide mineral, (Fe,Ni)3P, yellowish in color and predominantly found in iron and stony-iron meteorites. Schreibersite can also be found in a variety of other meteorites including some acapulcoites, aubrites, enstatite chondrites and achondrites, lunars, ureilites, winonaites and a smattering of other meteorite types like CM, CO and CB. Schreibersite Click on Term to Read More occurs throughout the meteorite. Structural evidence indicates the meteorite experienced a molten stage on its The body from which a meteorite or meteoroid was derived prior to its ejection. Some parent bodies were destroyed early in the formation of our Solar System, while others like the asteroid 4-Vesta and Mars are still observable today. Click on Term to Read More. Based on cooling rate models, the diameter of the parent body is estimated to have been ~100 km, taking ~50 m.y. for the In the context of planetary formation, the core is the central region of a large differentiated asteroid, planet or moon and made up of denser materials than the surrounding mantle and crust. For example, the cores of the Earth, the terrestrial planets and differentiated asteroids are rich in metallic iron-nickel. Click on Term to Read More to solidify. The 2.81 g partial slice of Willamette pictured above was sectioned from the 96.47 g mass shown below, previously purchased at the 2002 Macovich Auction in Tucson, Arizona. This 96.47 g mass was acquired for the Macovich Collection of Meteorites through a trade with the American Museum of Natural History in New York.
Photo of the 96.47 g section of Willamette from which the above specimen was sectioned
Photo courtesy of The Macovich Collection of Meteorites.
The heavily corroded rear side of the Willamette meteorite
Historical image of the Willamette iron meteorite in transport to the Hughes property