rockpassion
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I have bought this 61 gram unclassified XXX NWA years ago and just found it again in my collection. Is it a meteorite or a bust.
unclassified XXX NWA
- Thread starter rockpassion
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Simply showing pictures of what is believed to be a wholestone meteorite is not usually enough to enable a verification unless there are one or more obvious meteoritic features: aerodynamic sculpting such as regmaglypts; flow lines or other flight orientation features; an obvious fusion crust; or a number of other clues depending on meteorite type/classification. Or evidence of a witnessed fall with immediate recovery from an impact site.
Conversely, it’s sometimes the case that a stone can definitively be said not to be a meteorite based on obvious red flags which are uncharacteristic of meteorites.
At minimum, it’s also essential to give other information such as degree of attraction to a magnet and a streak test result. Exposure of the interior also helps, especially a polished window. Even then, these don’t necessarily enable a conclusive diagnosis.
Fresh fusion crusts are usually a rich black colour and relatively smooth; occasionally glassy with vesicles on the surface (only). The vast majority of NWA meteorites are from falls that took place a long time ago and fusion crusts are usually no longer black, but a deep brown colour from weathering and, although some pitting can often be seen, not usually to the extent seen on your specimen. That’s not to say your stone is not a genuine NWA, but it doesn’t have typical appearance and there simply isn’t enough evidence to say one way or the other.
You don’t say where you purchased this specimen but, personally, I would never purchase an unclassified meteorite from a source that I did not implicitly trust (ideally from an IMCA member and certainly not from a casual eBay seller) unless it had obvious features that I could recognise as meteoritic.
Conversely, it’s sometimes the case that a stone can definitively be said not to be a meteorite based on obvious red flags which are uncharacteristic of meteorites.
At minimum, it’s also essential to give other information such as degree of attraction to a magnet and a streak test result. Exposure of the interior also helps, especially a polished window. Even then, these don’t necessarily enable a conclusive diagnosis.
Fresh fusion crusts are usually a rich black colour and relatively smooth; occasionally glassy with vesicles on the surface (only). The vast majority of NWA meteorites are from falls that took place a long time ago and fusion crusts are usually no longer black, but a deep brown colour from weathering and, although some pitting can often be seen, not usually to the extent seen on your specimen. That’s not to say your stone is not a genuine NWA, but it doesn’t have typical appearance and there simply isn’t enough evidence to say one way or the other.
You don’t say where you purchased this specimen but, personally, I would never purchase an unclassified meteorite from a source that I did not implicitly trust (ideally from an IMCA member and certainly not from a casual eBay seller) unless it had obvious features that I could recognise as meteoritic.
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