Now, let’s talk about the not-so-exclusive qualities of a stony meteorite The same caveat applies with these as well: weathering can sneak in through surface cracks and eat away at chondrules and leave behind the vague outline of relict chondrules.Īn iron meteorite showing large thumb prints, or regmaglypts, on its surface (Image from Wikipedia) They’re not always visible in a hand sample, but if you see them with hand lens, you have a meteorite. No earth rock comes close to mimicking the appearance of these little spherical inclusions. Chondrules– I would say that these are the definitive characteristic of a meteorite.Just know that terrestrial rocks will not have a fusion crust. It can weather away if left to the mercy of earth’s climate for too long. One caveat though: not all meteorites will retain their fusion crust. If you see a rock with this characteristic you’ve got a meteorite. It’s also common to see a matte surface instead of a glossy one. The exterior starts to melt from the friction generated heat, and if the meteor is large enough to survive its bumpy ride, instantly cools to form a glassy, black surface. Fusion crust– This is the shiny black surface that forms on a meteor as it rockets through the earths atmosphere.So, let’s get into the first two definitive characteristics: Iron meteorites are obvious, so I won’t delve into those. These guidelines are only valid for stony meteorites. There is some leeway because meteorites are from the same material which the earth formed. With two exceptions, most of the differentiating criteria for meteorite identification are not set in stone (sorry… I couldn’t resist the pun). There are a few characteristics to look for when determining if you’ve found a meteorite. It actually makes for a great teaching moment. So, in no way am I denigrating those that hunt the space rock that I may end up studying. He was obviously passionate about his hunt as displayed by the number of locations he had visited during his meteorite search. To be fair, finding meteorites isn’t easy regardless of what it may look like on T.V. They all displayed the smooth contours that typify rocks of a fluvial environment. Instead he had some really nice river rocks. Unfortunately, the gentleman didn’t find a single meteorite. He obviously went to a lot of effort to collect these rocks and he was wanting us to tell him if any were meteorites. On these cards he noted where the samples came from, when they were collected, and most importantly, his assumption of what type of meteorite he found. In this box were about four large ziploc bags, each loaded with rocks that were cataloged on 3×9 index cards. My favourite cracked crust meteorite's is Ghadamis from NW Africa, Algeria, from memory.Last summer, when I did my first project with the meteorite lab, a gentleman had dropped of a box full of rocks. Surprisingly, the inside of the meteoroid doesn't heat up overly much. A fellow collector who does indepth meteorite studies commented that frost can form on the fusion crustĬausing the cracks and in extreme cases a layer of ice can form, making those cracks even more pronounced. This can be as it passes through particularlyĬool layers of the atmosphere. See the examples I posted from my collectionĬontraction cracking is caused the strong cooling high in the atmosphere, 15 - 20 km or so. Not all stone meteorites end up with a cracked fusion crust. I should have done so when I first read it. Then the inside cools and shrinks which partly closes the surface cracks.Īctually, I will clarify that comment. When the hot meteorite slows down and begins to cool in the lower atmosphere, the surface shrinks first, opening cooling cracks in the surface. This is because I have have not grinded window yet and secondly my camera quality is dull You need to remember that many Earth rocks are also attracted to a magnet including the two most mis-identified ones, Lunar and Martian breccias and the H.E.D series of asteroid achondrites. Irons, Pallasites and Chondrites are all attracted to a magnet with their varying amounts of iron and nickel that is presentĪchondrite meteorites have near to zero metal and are rarely attracted to a magnet. You can see all the little flakes of metal through the sample, this just doesn't happen with Earth rocks In Earth rocks and is a good indicator of a meteorite, this is what it commonly looks like in a chondrite meteorite. Stony meteorites often have metal flakes, this is a feature that is non-existent This is what they typically look like in a meteorite, normally a pallasite which also has lots of metalĪgain, I dont see any obvious metal flakes. I don't see any obvious yellow - green olivine crystals
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