12divenoro

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Oct 11, 2024
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2 meteorites?

roughly 5cm in diameter each
.
Extremely magnetic found in the desert Saudi Arabia,

both are positive to the nickel test.

Both are have a strong metallic shine when cut.

Very dense.

One of the meteorites looks like it has olivine veins in it. Are these meteorites and if so what type? Could they be man made?
@Red-Coat hopefully will answer your questions.

They look pretty good though from what has been posted up before.

Have you done a streak test yet on a ceramic tile?
 

Welcome to Tnet.

You potentially have some good indicators here. I would comment as follows:

  • The only common metallic items which are strongly attracted to a magnet are magnetite (of terrestrial origin) and man-made materials such as slag. Native iron with a metallic appearance is a rare terrestrial material and almost exclusively confined to the Northern hemisphere.
  • Deserts are good places to find meteorites and small isolated magnetic rocks in areas that are exclusively sandy with no rocky outcrops have a high probability of being meteorites.
  • Metallic slags can be dumped in all kinds of places but isolated finds in desert areas would be unlikely.
  • Positive tests for nickel are an encouraging sign, but most nickel testing kits are extremely sensitive and will give positive results for trace amounts (as well as being notorious for false positives).
Your pictures donā€™t enlarge well. The resolution is poor, and you havenā€™t shown the cut surface, which might be helpful.

As a next step, without resorting to professional testing, there are a couple of things you can try. Firstly, a streak test on the unglazed back of a porcelain tile. A meteorite will streak with difficulty, or not at all and skid off the tile. At best it might leave a weak dirty streak. Magnetite will streak easily and leave a dark grey mark which may have orange/brown hues from associated hematite.

Secondly, you can try etching it, to see if there is a Widmanstatten pattern from the Kamacite/Taenite crystallisation of its nickel-iron composition. For professional testing and display, nitric or hydrochloric acids are used but you can more easily check using a ferric chloride solution without the need for acids. Stores catering to home electronics such as ā€˜Radio Shackā€™ sell it as an etchant for circuit boards.

You need the cut surface to be sanded flat, then highly polished and thoroughly cleaned. A product such as ā€˜Cometā€™ cleanser should do the job, followed by washing under a tap with hand-hot water. Wipe it dry with a soft cloth and dab the ferric chloride (as a strong solution if making it from powder) onto the surface using a piece of cloth. If the surface excessively darkens, wipe it dry with the cloth to remove the excess colouration and wash again under the tap. Repeat the process multiple times, keeping the specimen warm. If there is a Widmanstatten pattern it will progressively emerge. Youā€™re looking for something like this:

Muonionalusta Etched Slice.JPG


Wash thoroughly with boiled or distilled water and thoroughly dry in a warm place for several days after youā€™ve finished testing to prevent future deterioration if it looks like it might be a meteorite. Acetone or alcohol will help drive out residual moisture.

Note that man-made slag may also produce a pattern of some kind, but not the distinctive Widmanstetten figures seen in meteorites. Itā€™s also not 100% conclusive since nickel-iron ataxite meteorites have no Widmanstatten features but thatā€™s a relatively rare class.
 

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