Stone meteorite5/18/2023 ![]() On stony meteorites, fusion crusts are seldom more than 1 or 2 mm thick. When it slows down to the point where no melting occurs, the last melt to form cools to make a thin, glassy coating called a fusion crust. A meteoroid loses most of its mass as it passes through the atmosphere. The melted portion is so hot and fluid that it immediately ablates (sloughs off) and new material is melted underneath. The hot air causes the exterior of stony meteoroids to melt. When air is compressed rapidly, its temperature increases, like air in a bicycle tire pump. At those tremendous speeds, the air in the path of the rock is severely compressed. Meteoroids, i.e., small rocks orbiting the sun, enter Earth’s atmosphere at speeds of many miles per second. It might be a meteorite, but I am not going to suggest to you that it is. If you send me a photo of a rock that does not have a fusion crust, then I am not going to mislead you by saying that it is possibly a meteorite. If a rock does not have a fusion crust and does not contain iron-nickel metal, then there is no reason to suspect that it is a meteorite, regardless of what other meteorite-like features it may have. A fusion crust is the most characteristic feature that distinguishes a meteorite from a plain old Earth rock. Note the lighter colored interior on upper right where the rock has been chipped away. Fresh meteorite fusion crusts are smooth, shiny, glassy, and darker colored than the inside of the meteorite. More photos people have to sent me of things that look like meteorites Stony meteorites One of the Camel Donga stones from Australia.
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