Yesterday Jan and I took a new ultra-magnification photo of micrometeorite NMM 828. The stone is a “giant” micrometeorite, 0.5 mm long, and the new photo is 24,000×24,000 pixels, two and a half meters wide, which is almost exactly 5,000 times magnification!
This allows us to admire the strange extraterrestrial rock’s previously unseen details. When I found it I could not believe that this could be a micrometeorite, so it has been thoroughly analyzed, and it is indeed chondritic. The stone is a very low heated micrometeorite with chunks of nickel-iron and sulfide all over the surface, so it has not completed an elemental differentiation. It is closer to what cosmic dust looks in space than most cosmic spherules retrieved on Earth. Several places in the fine-grained matrix there are holes from incomplete degassing of volatile elements. Note on the scanning electron microscope (SEM) image how the inside of one of the “chimney holes” are covered in sulfides, which appear white in the backscatter SEM image. Note also the angular area to the left. Is that hiding a reflect grain?
A couple of areas on the surface have well developed olivine (forsterite) crystals, but in my view not enough to classify the stone as porphyritic olivine (PO-type) micrometeorite. At the same time there are very little (hardly any) magnetite ochtahedron crystals on the surface, indicative for scoriaceous (SC-type) micrometeorites if I’m not wrong. So what is this? Something in the middle?
Even in the compressed image in this blog post and corresponding social media posts, there are details here hardly seen this clear before. Enjoy!
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