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|Title: ||Port Orford, Oregon, Meteorite Mystery|
|Authors: ||Clarke, Roy S., Jr.|
|Issue Date: ||4-Jan-1993|
|Citation: ||Smithsonian Contributions to the Earth Sciences; 31|
|Abstract: ||The Port Orford meteorite was allegedly discovered by John Evans, a contract explorer for the United States Government, on a mountain in southwestern Oregon in 1856. Efforts to organize the recovery of the alleged 10-ton body for placement in the Smithsonian Institution in Washington, D.C., began in late 1859, but were abandoned as a consequence of the simultaneous onset of the Civil War and Evans' death.
Early in this century journalistic reports revived the story and stimulated numerous unsuccessful amateur meteorite hunting expeditions into the inaccessible Siskiyou National Forest. Smithsonian investigators visited the vaguely defined site without success in 1929 and 1939. As time passed, it became increasingly obvious to some involved officials that there was something wrong with the original accounts. Nevertheless, most persons persisted in their belief that Evans' story was true.
This monograph combines an historical study by Howard Plotkin ("John Evans and the Port Orford Meteorite Hoax," pages 1-24), and a technical study by V.F. Buchwald and Roy S. Clarke, Jr. ("A Mystery Solved: The Port Orford Meteorite is an Imilac Specimen," pages 25-43).
In the first paper, Plotkin details the history of the mysterious lost Port Orford meteorite, and presents previously unreported evidence that indicates Evans was ill-trained for his scientific field work, which was superfically and unprofessionally executed, and that he had amassed a staggering personal debt by consistently overspending his budget. Most startling of all, Plotkin's research led him to the inescapable conclusion that Evans had acquired a small but very rare piece of meteorite, and had hatched a clever scheme whereby he could use it to turn around his financial affairs. Plotkin reconstructs in detail how Evans planned to carry out this hoax.
Finally, Plotkin endeavors to establish the true identity of the meteoritic sample. On the basis of its overall physical appearance, degree of weathering, and chemical composition, Plotkin argues that the Port Orford specimen is a fragment of Imilac, a Chilean pallasite discovered in 1820-1822. He further contends that Evans acquired it from someone else while crossing the Isthmus of Panama on his final return trip from Oregon during the fall of 1858.
In the second paper, Buchwald and Clarke describe the involvement of the National Museum of Natural History in attempts during this century to recover the meteorite, and they report on their detailed technical studies of the Port Orford specimen and other possibly related meteorites.
Buchwald and Clarke point out that only three distinct pallasite falls were known in the late 1850s: (1) the single Krasnojarsk, Siberia, mass, (2) the two large masses of the Brahin, Belorussiya, meteorite, and (3) the Imilac, Chile, shower. Both Krasnojarsk and Brahin were ruled out of a possible hoax scenario on the basis of physical properties and state of corrosion, which left Imilac as the only possibility short of invoking an otherwise completely unknown fall. They therefore undertook detailed metallographic and mineralogical examinations of the Port Orford specimen and several Imilac specimens in an attempt to resolve the matter.
They find that the Port Orford specimen is a main group pallasite that is chemically, structurally, and morphologically indistinguishable from Imilac. The steep thermal gradient of its heat-altered zone shows it to be an individual from a shower-producing fall and that it could not have been a specimen removed from a large mass. Its weathering history suggests the arid conditions of the high desert of Chile, not the humid Oregon coast forests. Port Orford's kamacite composition and hardness, olivine composition, trace element levels in metal, and shock levels in kamacite and troilite are all within observed ranges for the Imilac shower or within reasonable extensions thereof. These many congruencies led Buchwald and Clarke to conclude that the Port Orford meteorite is an Imilac specimen, and that Evans perpetrated a deliberate hoax using a small Imilac individual as bait.|
|Appears in Collections:||Smithsonian Contributions to the Earth Sciences|
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