unclassified XXX NWA

[rockpassion]

I have bought this weathered 61 gram unclassified XXX NWA years ago and just found it again in my collection. Is it a meteorite or a bust.

 

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[vpnavy]

...meteorite or a bust.

Until a member pipes in - here are a few informative articles talking about meteorites...

About Meteorites​

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Aerolite Meteorites
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How to find out if you have a Meteorite?​

 

[BennyV]

Looks legit to me but I am not an expert in space rocks.

 

[Red-Coat]

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.

 

[rockpassion]

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.

Oke thanks for your answer, there is allot to do for me before we can go further. The caracteristiks of the stone are heavy for it's size, atracts a magnet and has orange yellow crystals in the brown matrix. it has a sort of triangular pyramid shape and , and leaves barely a streak but leaves a grey powder behind. no metal flecks in the window. See whole stone and 2 photo's of grind in window. Looks like a ureilite i think.

 

[Red-Coat]

Well, so far so good but…

Funny how when folks think they have a meteorite, but which doesn’t have a typical common appearance, their fall-back position is usually “it must be a rare type” (ureilite, diogenite, lunar, martian or whatever).

If it is a meteorite it’s obviously not an ordinary chondrite. What were the credentials of the seller (you ducked that question)? Anyone who knows anything about meteorites would not be selling a stone as a generic NWA if there was any suspicion it could be a more valuable type than the usual chondritic specimens.

I specifically said that the important information is “degree of attraction” to magnet, but you have only said that it’s attracted, without saying how strongly.

Note also that a ureilite would not be particularly notable for being “heavy for its size” when judged in the hand. Ureilites typically range between Specific Gravities of 3.2 – 3.3 versus most crustal Earth rocks at between 2.6 – 2.7 and magmatic rocks such as basalts between 2.8 – 3.0 or a little beyond. Rocks rich in hematite can be considerably more dense since hematite has a S.G. of about 5.3, but the streak test would have told you straight away if there had been a significant hematite content.

So, as things stand it’s a “possible” but, if so, of a classification for which no amount of looking is going to be able to confirm. Professional testing would be needed, but if you know someone who has an XRF gun that might help.

 

[rockpassion]

Well, so far so good but…

Funny how when folks think they have a meteorite, but which doesn’t have a typical common appearance, their fall-back position is usually “it must be a rare type” (ureilite, diogenite, lunar, martian or whatever).

If it is a meteorite it’s obviously not an ordinary chondrite. What were the credentials of the seller (you ducked that question)? Anyone who knows anything about meteorites would not be selling a stone as a generic NWA if there was any suspicion it could be a more valuable type than the usual chondritic specimens.

I specifically said that the important information is “degree of attraction” to magnet, but you have only said that it’s attracted, without saying how strongly.

Note also that a ureilite would not be particularly notable for being “heavy for its size” when judged in the hand. Ureilites typically range between Specific Gravities of 3.2 – 3.3 versus most crustal Earth rocks at between 2.6 – 2.7 and magmatic rocks such as basalts between 2.8 – 3.0 or a little beyond. Rocks rich in hematite can be considerably more dense since hematite has a S.G. of about 5.3, but the streak test would have told you straight away if there had been a significant hematite content.

So, as things stand it’s a “possible” but, if so, of a classification for which no amount of looking is going to be able to confirm. Professional testing would be needed, but if you know someone who has an XRF gun that might help.

weakly atracts a magnet, bought it years ago on a minerals show here localy and it does not exist anymore. from a morrocan mineral dealer. don't think he was IMCA but it was in the 80's. So all we know if it is a meteorite it is a achondrite type needs more research with xrf. sadly don't have that opurtunity. And to quote
Funny how when folks think they have a meteorite, but which doesn’t have a typical common appearance, their fall-back position is usually “it must be a rare type” (ureilite, diogenite, lunar, martian or whatever). What else is there but those you mentioned