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Odessa   contributed by Steve Brittenham, IMCA 2184   MetBul Link


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View all entries for   Meteorite (13)   Steve Brittenham (108)


Copyright (c) Steve Brittenham.
  Iron, IAB-MG

TKW 1.6 tons. Fall not observed. Found 1922 near Odessa, TX, USA.


   


Steve writes:
Sometime around 25,000 to 50,000 years ago a huge meteor weighing between 500 and 1500 tons exploded mid-flight 10 miles southwest of present day Odessa Texas, showering the countryside with meteorites and leaving a roughly 600 foot diameter crater along with several smaller adjacent ones. Today the rim of the largest crater still rises over five feet from the surrounding plain, but wash and wind-blown material have since filled the depression to less than 15 feet from the top. In 1892, rancher Julius Henderson stumbled onto it while searching for a lost calf but thought it was merely a common topographic "blowout". Then in 1920 Ector County resident Virgil Graham found an odd rock near the crater and gave it to Samuel R. McKinney, who initially used it for a paperweight before Baltimore geologist A. C. Bibbins saw it in McKinney's office and recognized it as a meteorite. But it was the Bureau of Economic Geology’s Elias Sellards that finally identified the actual meteor crater while searching for potash in 1922 – an identification confirmed in the late 1920s by lawyer and mining engineer Daniel Barringer who also discovered Arizona’s Canyon Diablo crater.

Geologists converged on what became known as Ector County’s Odessa Meteor Crater in 1939 and spent 24 months studying it and the smaller, wash-filled craters they found with a magnetometer while searching for the meteorite’s main mass 1. Approximately six tons of smaller meteorites were unearthed during the excavation of the main crater, but an 8 foot by 12 foot shaft dug 165 feet deep – 5 feet under the bottom of the original crater – failed to yield any remnants of the original meteorite 2. After two years of searching, project supervisor Glen Evans finally conceded the main body must have vaporized upon collision 3. Undaunted, Evans later went on to study meteorite craters throughout the world and even explored the possibility that the Odessa Crater may be associated with the Barringer Crater in Arizona, noting they are very similar in age and material and pointing out that meteors are known to come in clusters (citing central Australia’s group of thirteen, four in Argentina, and seven in Russia as examples) 4.

The Odessa Meteorite Crater was designated a National Natural Landmark in 1965, though prior to that the Odessa Chamber of Commerce had formed a committee known as the Odessa Meteor Crater Task Force to consider the best ways to develop and protect the site. But that task force has been inactive for some time, so numerous meteorite hunters have been able to scour the area and provide a plentiful supply of Odessa meteorites to collectors.

This particular example was acquired locally from a fellow who had inherited it from his grandfather but who had no real interest in meteorites. He had gotten my name from a local rock shop and asked that I come over, if not to buy it, then at least to give him an idea of its worth. He had the original 1973 paperwork from his grandfather’s purchase, but as seen in Photos 1 and 2, oxidation had badly affected the surface, creating a moss-like pattern as the rust worked its way under the clear coating used to protect the cut face. I thought it might be fun to try to restore it myself (I had never etched a meteorite before), so I made him a reasonable offer considering its condition and he accepted it. I used acetone to first dissolve the surface’s clear coat, then polished it to remove the oxidation; and because I was going to the Portland area on vacation, I drove south a few miles to visit Edwin Thompson (of E.T. Meteorites), who was kind enough to show me how to etch it. The post-etched photos were taken fairly recently, demonstrating that in the five years since its reconditioning, the oxidation has not returned (Photos 3 and 4 were taken at different angles to better display the Widmanstӓtten lines; Photo 5 shows the back side of the meteorite; and Photos 6 and 7 blow up some of the various inclusions that are so plentiful in Odessas.)

Footnotes
1 Their work was so intense that when Harvey Ninninger visited the site, he called what he saw “Odessecration”.

2 The Odessa crater contains most of the classic astrobleme features associated with impact craters, including strongly tilted rocks on the periphery and a central mound of boulders. Also found within the shaft were fossils of Pleistocene horses and elephant teeth above the fragmented bedrock, giving early investigators some idea of the age.

3 Almost half a century later Evans reflected on the excavation, commenting that "A vast incongruity exists regarding meteors. The biggest meteorites, when they're found in the ground, are in the smallest craters, and in the largest craters you don't find any meteorites at all."

4 Later, meteorites from both falls would be shown to be compositionally identical and scientists would model the Barringer and Odessa craters to demonstrate that a single meteor could have initially broken into two major pieces, the first further fragmenting and falling over Arizona, while the second continued on to explode over Texas.
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Ben Fisler
 5/22/2017 7:40:51 PM
Beautiful etching - makes that great specimen "shine".
Steve Brittenham
 5/21/2017 12:53:45 PM
Hi Adri*n. Thanks for the nice comments, and also for your comments regarding La Criolla a few days ago. I'm sorry I wasn't able to acknowledge them then, but I was traveling all day.
Adri*n Contreras G*mez
 5/21/2017 7:08:20 AM
Muy interesante. Bonito ejemplar. Enhorabuena
 

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