larense Posted July 21, 2007 Share Posted July 21, 2007 Hola, again forists. Here we have a NWA 4528 H5 S2 W 2/3 ( provisional ) meteorite of 64.4 grams ( first picture ). Now, again we found, looking closely to its surface, these rounded grains of different colors imbedded in the fusion crust ( second and third pictures ). The fusion crust in this area, seems to have boiled and exposed this grains or ¿ chondrules ?. Any opinion is wellcome. Hasta la vista, larense Quote Link to comment Share on other sites More sharing options...
larense Posted July 22, 2007 Author Share Posted July 22, 2007 Hola forists. A good geologist friend from our country, has speculated that the grains looks like microtektites, cause chondrules are an aggregate of cristals of olivine and pyroxenes....and he think they could have formed up by inter asteroids colision in the highway of the asteroidal belt. WOW.....a meteorite with microtektites....never heard of it before. Any other opinion are still wellcome. Hasta la vista, larense Quote Link to comment Share on other sites More sharing options...
larense Posted July 23, 2007 Author Share Posted July 23, 2007 Hola forists. Mr Whymarck wrote : I am almost certain these are sedimentary quartz grains. This would lead me to the conclusion that either this is not a meteorite, but an ironstone instead (although you seem pretty confident that it is a meteorite and I assume it is strongly attracted to a magnet - if not (or only very very weakly) think again). If sliced and these grains occur througout then it isn't a meteorite. Assuming it is a genuine meteorite I would suggest that it has simply rusted and in doing so has incorporated sand from the ground it was sitting on/in into the oxidised crust. These grains certainly do not appear to be meteoritic or microtektites. Regards, Aubrey ................................................................................ ................................................................................ ..... We replied to him : Hola Mr. Whymark. Thank you so much for your fast reply. We bought 1, 500 grams of this meteorite from a well known meteorite dealer ( Mr. G. Hupe ). This time , we did our best to take pictures of this patchy- effervescented- black- that- lodge- the- grains area on the meteorite surface, which is different from the normal brown-black-rusted fusion crust of this individual ( other specimens of the lot also have the patchy- effervescented- black areas ), and you can see how well delimited they are and how well sticked they are to the meteorite surface ( in one of the pictures the grains are lodged in a rounded and eroded patch ). This have puzzeled us, cause we thought it could be a dessert patina or dessert varnish...but we are still puzzeled up. Unfortunately, we do not have a cutting stone machine, but we can assure you , we have sanded corners of some specimens and a brecciated matrix with chondrules and metal specks, have appeared and the stones are strongly magnetic. We will soon recieve a slice of this meteorite, and a picture of it, we are also including in this reply. The question is still up : ¿ What is this patchy- effervescented-black area on the meteorite ? Our best regards, ................................................................................ ................................................................................ ......... Quote Link to comment Share on other sites More sharing options...
larense Posted July 24, 2007 Author Share Posted July 24, 2007 Hola, forist. Among many answers we received , these below, may respond the how, why, when or what of the dessert weathering process meteorites suffer after resting for 6,000 to 10,000 years on that geographic place. You have a meteorite from NWA (judging from the desert varnish and weathering) with quartz grains that have adhered to its surface due to the weathering process in the desert. The meteorite was partially buried and as water (rain and dew) interacts with the iron in the meteorite the sand adheres. The quartz is stained by the iron so the quartz turns brown, rusty brown or yellow. This is very common in deserts finds. I hope that this answers your question. Best Always, Dirk Ross...Tokyo ................................................................................ .............................................. The terrestrial age of many NWA meteorites is thought to be 6,000-10,000 years; for sand to adhere depends on the amount of water available and the terrain in which in fell. In a very dry environment such as the Sahara has now,it would take much longer than 6,000 years ago when the Sahara was wetter. Normally seasonal winds bury and uncover meteorites as the general wind direction changes usually twice a year. I cannot answer your question as to how long this particular meteorite took to develop sand encrustation; perhaps no one will know for sure unless the meteorite`s terrestrial age is known. There are too many factors as mention above than can produce this result. Sorry I cannot be of much help. Best, Dirk Ross...Tokyo ................................................................................ .................................................... Hi I agree from the interior that these are definitely meteorites - also the Hupes certainly would not sell dodgy material. I am almost certain that the material is sand/grit from the desert that has simply rusted to the specimen. It looks like quartz (i.e. not meteoritic). You will agree that the meteorite is quite oxidised and will readily rust and incorporate surrounding grit. The clear delineation of this surface texture is easy to explain. Where this sand/grit is attached to the meteorite is where it was half buried and represents the buried portion. This appears more rusty because a) it was exposed to more water as it was in the soil so not as easily dried out by the sun and b) the other (exposed) half of the meteorite was subject to sand-blasting by wind-blown sand grains. Look at the line between the 'bubbly' area and the normal brown 'fusion' crust. I am sure you will be able to trace it around the specimen. The rust part incorporating quartz grains was buried. The normal part (a heavily oxidised 'fusion' crust) is sand-blasted exposed area. Thanks, Aubrey Whymark ................................................................................ ......................................................... Hasta la vista, larense Quote Link to comment Share on other sites More sharing options...
larense Posted August 5, 2007 Author Share Posted August 5, 2007 Hola forists. Our european friend, Martin Altmann, wrote his opinion : Hidiho from Romania, that are quartz-like looking grains and are sand grains deposited in the deser varnish of the stone. Best! Martininho Hasta la vista. larense Quote Link to comment Share on other sites More sharing options...
larense Posted August 5, 2007 Author Share Posted August 5, 2007 Hola again, forists. We finally recieved the NWA 4528 H5 S2 W2/3 meteorite slice ( the pictured on pink background - Ebay seller posting ). But here , we will upload , the ones we took.....a really nice chondrite. Hasta la vista, larense Quote Link to comment Share on other sites More sharing options...
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