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Black As Coal . Hard As Rock. Ordinary As a Chondrite

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Black As Coal . Hard As Rock. Ordinary As a Chondrite Meteorite-Times Magazine Contents by Editor Like Sign Up to see what your friends like. Featured Monthly Articles Accretion Desk by Martin Horejsi Jim’s Fragments by Jim Tobin Meteorite Market Trends by Michael Blood Bob’s Findings by Robert Verish IMCA Insights by The IMCA Team Micro Visions by John Kashuba Galactic Lore by Mike Gilmer Meteorite Calendar by Anne Black Meteorite of the Month by Michael Johnson Tektite of the Month by Editor Terms Of Use Materials contained in and linked to from this website do not necessarily reflect the views or opinions of The Meteorite Exchange, Inc., nor those of any person connected therewith. In no event shall The Meteorite Exchange, Inc. be responsible for, nor liable for, exposure to any such material in any form by any person or persons, whether written, graphic, audio or otherwise, presented on this or by any other website, web page or other cyber location linked to from this website. The Meteorite Exchange, Inc. does not endorse, edit nor hold any copyright interest in any material found on any website, web page or other cyber location linked to from this website. The Meteorite Exchange, Inc. shall not be held liable for any misinformation by any author, dealer and or seller. In no event will The Meteorite Exchange, Inc. be liable for any damages, including any loss of profits, lost savings, or any other commercial damage, including but not limited to special, consequential, or other damages arising out of this service. © Copyright 2002–2010 The Meteorite Exchange, Inc. All rights reserved. No reproduction of copyrighted material is allowed by any means without prior written permission of the copyright owner. Meteorite-Times Magazine Witnessed Fall: Tadjera, Algeria by Martin Horejsi Like Sign Up to see what your friends like. A June 1867 Witnessed Fall: Tadjera, Algeria The Tadjerites: Black as Coal . Hard as Rock. Ordinary as a Chondrite. One hundred forty-three years ago this month, “A luminous body was seen to descent towards the earth, and when arrived at a certain height to burst into fragments.” The report published August 5th, 1867 continues, “The flash of light was followed by rumbling noises, which ended in three loud reports, and were attended by a fall of aerolites.” The fall, having landed on the Plain of Tadjera, Amer Guebala, near Setif, Algeria, was therefore named Tadjera. Algeria is a large place. Covering a portion of the globe roughly three and a half times the size of Texas, Algeria claims only seven meteorites whose falls were witnessed. Interestingly, four of the seven falls occurred during the 25 year period between 1865 and 1890 with two more falls in the 1940s, and the most recent landing in 1989. In specific, the Tadjera meteorite fell at about 10:30 P.M. on June 9, 1867 about 15 kilometers southeast of the town of Setif in eastern Algeria. Two stones from the Tadjera fall were recovered, totaling about 8 kilograms. Most of the material went to the Museum National d’Histoire Naturelle in Paris because Algeria was under the rule of France at that time, but, according to the late Brian Mason, “the meteorite is represented by small pieces in a number of collections.” I am honored that one of those collections is mine. Just a whole lot of nothing? If black is the absence of color, then Tadjera is almost a negative meteorite. Even in this color inverted image, not much happening. No wonder Meunier considered Tadjera for a new class of meteorite. For a hot desert fall, Tadjera sure got around quickly. The famous meteorite scientist Gabriel- Auguste Daubrée (1814–1896) examined Tadjera in 1868. And three years later Stanislas Meunier used the chemical analysis tools of his day and assigned the Tadjera to a distinct type of chondrite that he named the “Tadjerite.” Although chemical tests were done, the “classification” of Tadjerite was due mostly the physical characteristics of light reflectance (low) and the degree to which Tadjera resists breakage (high). A pot calling the kettle black? Covering a black meteorite with black crust hardly jolts the excite-O- meter, but it is an interesting situation when you cannot see a clean dividing line between crust and matrix. Often, the deep contrast between the exterior and interior of a suspected meteorite is considered an important indication of authenticity. However, in this case the crust is almost indistinguishable from the matrix. So specifically, according to Meunier, Tadjerites are identified by their black color and their hardness. The Tadjerite class had only one member until the Farmington meteorite fell in Kansas in 1890. However, the chemical connection between the two would have to wait another three quarters of a century. And when that analysis was done, yet a third meteorite joined the Tadjerite clique, and that was Bath, South Dakota, a 1892 fall. Interestingly, when the late Dr. Mason was studying Bath in 1966, it piqued his interest and he went back to the lab to study Tadjera since the initial analysis of the stone was somewhat primitive given the standards of the day. Two Tadjerites: Tadjera on the left and Farmington on the right. I have to agree that there are many visual similarities. Both are fresh witnessed falls of L5 chondrites, but a tipping point was reached when enough similar chondrites entered our collections to show us that in essence, the “Tadjerites” are just one end of the continuum of chondrite appearances. According to Mason, “The black color, the highly indurated condition, the disseminated troilite, and the disordered pyroxene all suggest that the Tadjera meteorite was subjected to intense shock some time during its extraterrestrial history.” This is all very interesting given that Farmington has attracted attention because of its short cosmic-ray exposure and a prime suspect in a gang-related drive-by shooting on the Moon in June of 1975. Oberst (1989), suspecting that Farmington “may have been a member of a large meteoroid swarm which was detected by the Apollo seismic network” described the circumstantial evidence in the case as, “The association implies that the parent body of the Farmington meteorite was in an Earth-crossing orbit at the time the swarm was formed. This supports the idea that at least some meteorites are derived from the observable population of Earth-crossing asteroids.” The three fall dates of potential Tadjerites, 1867, 1890 and 1892 are an curious cluster. Given the proximity in time and space of the Tadjera, Farmington, and Bath falls as well as their similar chemical tattoos and other gang colors, it is likely that they shared the same ‘hood’ prior to tagging the Moon. A rich collection history is always a bonus. In the case of this particular specimen of Tadjera, it entered the Schwade Collection 23 years ago being purchased from David New in January of 1987. The painted specimen number, S253, is from the James Schwade Collection. The number 253 likely represents the two-hundred fifty third meteorite in Dr. Schwade’s collection. So it is easy to see that he was well on his way to building a world-class collection long before the explosion popularity of meteorite collecting in the mid to late 1990s. Tadjera is one of those specimens that entered my collection more through convenience than desire. Yes, I did choose the specimen from a list, and yes, it was because of the historic fall date and low TKW of this fall, and yes, the fact that the name Tadjera was one I had not come across before (which is always exciting), but the coincidence that I acquired it just as the proliferation of hot desert material was at a crescendo and that this stone claimed Algeria as home did give me pause. However, in hindsight I have grown comfortable with the knowledge that I can love a hot desert chondrite as much as anyone else. It’s just that my love is for is a 143 year-old hot desert witnessed fall that for a brief time, was its very own meteorite class.. Until next time…. The Accretion Desk welcomes all comments and f eedback. [email protected] Please Share and Enjoy: Meteorite-Times Magazine Meteorite Collecting Broadening the Experience by Jim Tobin Like Sign Up to see what your friends like. I mentioned recently that my collecting habits have changed toward falls. Well, I was adding a couple of new specimens to my database and decided to see how many falls I actually had. Boy was I surprised when I found that I had jumped all the way to nearly 30% falls in my collection. It has not been that long ago that I was probably near 10-15%. I do like the stories and added information that accompanies falls. It really brings me closer to the event. Now with all the modern technology involved that closeness is likely to just increase for the next generation of collectors. It is becoming common place to include along with the newspaper reports the doppler radar data and video of the fall as part of the specimen‘s presence in collections. Many specimens now come with gps information on where it was exactly found in the strewn field. I love that. It is like a time warp for me. Instead of recording gps when I find a specimen after thousands of years of terrestrial hiding I get gps on a space rock only days after landing. Knowing who found it and exactly where is another way I get more connected to the whole experience. But, I think it is pretty unlikely that I am going to begin collecting just falls.
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