Identify if a Meteorite? Fusion Crust, Magnetic, Olivine

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The discussion revolves around the identification of a rock suspected to be a meteorite. Key characteristics mentioned include fusion crust, magnetism, metal flakes, and the presence of orange olivine crystals. However, participants express skepticism about the rock's meteorite status, emphasizing that it lacks definitive signs typical of meteorites, such as a true fusion crust and observable olivine crystals. The rock is suggested to resemble an Earth rock, possibly a dense basalt, which can also exhibit magnetic properties and olivine crystals. The importance of providing clear photographs for accurate identification is highlighted, as well as the need for geological analysis by a professional to determine the rock's true nature. Overall, the consensus leans towards the rock being of terrestrial origin rather than a meteorite.
  • #31
Het Patel -
Like the others, overall it does not strike one as meteoric origin.
Looks more like a dense basalt that's been river tumbled into the shape it now has.
Basalt can be magnetic since it's rich in iron.
It can also have olivine crystals which colors can vary.
A local university with a decent geology department should be able to thin section it and put it on a petrographic microscope which will definitively answer the question.
 
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  • #32
Baluncore said:
When the hot meteorite slows down and begins to cool in the lower atmosphere, the surface shrinks first, opening cooling cracks in the surface. Then the inside cools and shrinks which partly closes the surface cracks.
Actually, I will clarify that comment. I should have done so when I first read it.
Not all stone meteorites end up with a cracked fusion crust. Some are, most are not. See the examples I posted from my collection
near the start of the thread.

Contraction cracking is caused the strong cooling high in the atmosphere, 15 - 20 km or so. This can be as it passes through particularly
cool layers of the atmosphere. A fellow collector who does indepth meteorite studies commented that frost can form on the fusion crust
causing the cracks and in extreme cases a layer of ice can form, making those cracks even more pronounced.

Surprisingly, the inside of the meteoroid doesn't heat up overly much. Rock is a very good heat insulator.

My favourite cracked crust meteorite's is Ghadamis from NW Africa, Algeria, from memory.
This is a 1.45kg sample.

Brett Joseph 1.45kg Ghadamis2.jpg
 

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