How to ID / Identify a Meteorite - Stone

if you've ever found an odd Rock and think it could be a meteorite you're not alone every year thousands of odd rocks are found by ranchers farmers hunters and others and they all think they're potentially meteorites but the cold hard truth is less than 1% 1% is actually going to be a meteorite so here's some tests you can do in the field to see if you have a potential meteorite or a definite meteor wrong here are some tests you can perform before you bother University or lab with your rock you will need a magnet a grinder and a magnifying glass and the grinder can either be a diamond file or a spinning grinder bit on a drill that's portable for the field now then on to the tests the first test is the magnet test this is where we will test the stone for its ferrous component using a magnet the second test is the surface test also known as the texture test where we will look at the surface of the stone to see if it has meteoritic features the third test is the window test that is where we are going to grind a window or a flat spot onto the rock so that we can see inside the rock to see its matrix now then let's move on to number one because meteorites have iron they attract a magnet now you need to find or buy a decent magnet the flexible ones that have ads on them are very poor that's just like a magnetic cloth fridge magnets are better as long as they're the fixed stiff magnets rare-earth magnets are the best they are small tiny circular buttons that look like lithium batteries they have the highest Gauss rating for attracting metal ideally you want to hang a magnet on a string it enhances the sensitivity of the magnet the very first test you should ever do to a suspect rock that could be a meteorite is the magnet test it's such a great test that many meteorite hunters bring magnets out in the field with them hopefully you have your magnet suspended from a string which gives it extra sensitivity and what you're going to do is to hold the string with the magnet coming down until it's still and then you bring the rock to the mat magnet not the magnet to the rock this is so that if the rock happens to have a small amount of iron in it this magnet will actually swing over a little bit and deflect and you're able to see it has some iron in it if you just had a magnet without a string you'd bring the rock to the magnet and you wouldn't feel anything with your fingers but the string will let you see that there actually is a iron component to the rock now on the flip side because the rock does show some content of iron it does not mean it is a meteorite it's simply if it shows no iron content then it can't be a meteorite there are plenty of terrestrial rocks that have a ferrous component to them which is why we have the second and third test on the surface test we are actually going to be looking at the surface features of the stone we are looking at the texture of the surface we are looking for possible pinheads of iron flecks on the surface and we are looking for contraction cracks on fresh stones not all meteorites look the same they start out black but because of the iron they begin to rust and they turn reddish and then reddish brown and finally they turn into a deeper Brown and that's how they're normally found the starting skin of all meteorites is the fusion crust it's the burnt surface that occurred to that stone as it passed through the atmosphere at 30 to 40 thousand miles an hour now this fusion crust this skin that burned often has contraction cracks on it but you will only see those on fresh meteorites any holes on the surface of a stone pretty much condemns it because meteorites do not have holes if it looks like a lava rock nice and melted it probably is lava it is not needy right to pass the meteorite surface feature test we need to see surface features that are compatible with meteorites as in no sharp edges as in a fairly nice smooth feature over it but the actual texture of the surface is slightly rough and it needs to have no vugs or holes like lava rocks now the time to do the window test now take your grinder or your file or whatever tool you brought to make a small window meaning a flat spot about the size of a thumbnail which is about 2 or 3 square centimeters into the rock and that is going to become a window to see what the rocks matrix is made of you cannot see the matrix through simply a broken face in the rock you have to grind it down to a fairly flat polish of roughly 40 grit or better now what you're looking for is iron flecks or shapes of chondrules if it's an older weathered stone it may not have any iron left but you will be able to recognize chondrules they are looking like small babies that are off colored from the background matrix and they clearly show a pattern of roundness in the middle of nothing note the different types of matrices you can see in a meteorite you're looking for something that looks like this in your window you

Channel: OutofaBlueSkyMeteor

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Keywords: meteor, identification, id hunt, field, test, check, meteorito

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Length: 8min 32sec (512 seconds)

Published: Tue Nov 23 2010