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tvanwho

Meteorite Identification 101

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I eyeballed/ picked up a rock that looks sorta like an Apollo space capsule from a farm field.It has a paper thin black crust and grey interior where a farmers plow broke it, but my magnet won't stick to it. How do I tell if it is or isn't a meteorite? There is a parking lot there now.

There are sparkles inside the rock. I hear there are stony meteorites that are not magnetic? I'll find the rock and post a photo later.

 

-Tom

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On 3/22/2017 at 4:44 PM, tvanwho said:

I eyeballed/ picked up a rock that looks sorta like an Apollo space capsule from a farm field.It has a paper thin black crust and grey interior where a farmers plow broke it, but my magnet won't stick to it. How do I tell if it is or isn't a meteorite? There is a parking lot there now.

There are sparkles inside the rock. I hear there are stony meteorites that are not magnetic? I'll find the rock and post a photo later.

 

-Tom

Not to be a negative nellie here, but...

there are three things in the description of your stone that tell you it most likely is not a meteorite:

1. "It has a paper thin black crust and grey interior..." While most stony meteorites do have a dark fusion crust and lighter colored interior, the fact that your stone's exterior is black raises a red flag. Only a freshly fallen meteorite has a black fusion crust. Once the stone is exposed to the elements for any length of time, its exterior quickly oxidizes to a dark reddish brown color. A freshly fallen meteorite would have been immediately preceded by a fireball, sonic booms, etc. The chances of finding a fresh meteorite without eyewitness accounts and/or doppler radar data to guide you to it are next to zero. The black crust on your stone is most likely a manganese oxide coating.

2. "...my magnet won't stick to it." While there are stony meteorites that aren't attracted to a magnet, they are exceedingly rare. This alone tells you that it most likely is not a meteorite.

3. "There are sparkles inside the rock." Stony meteorites don't have crystalline components large enough to see without magnification and therefore never sparkle. Sparkly stones are definite meteorwrongs.

 

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Sorry, had some camera memory card and adapter issues. And I just got a newsletter from Lizzadro Lapidary Mineral Museum near me in Elmhurst,Illinois. They are having a meteorite ID class on April 22. I will be sure to attend and take this rock. Heck, I tried to grind off a flat spot on the rock to etch with acid. But cannot get a mirror finish and have no nitric acid so it will have to wait.

IMG_2972.JPG

IMG_2975.JPG

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Thanks for posting the photos Tom. The acid etching you mentioned only works on the solid metal variety of meteorites, so all you need to do is file or grind a window into your specimen and sand it smooth. If your rock is a chondrite without metal grains, the window should show round chondrules similar to the photo:

IMG_0780.JPG.5f1e7973de966bfeee777d142efa29ca.JPG

These chondrules are small, typically less than a millimeter in diameter. If there are no chondrules, the only possibility left is an achondrite meteorite. These can only be definitively identified by laboratory chemical, petrologic and petrographic analysis. Here's a list of meteorite testing labs:

http://meteorite-identification.com/verification.html

Best of luck!

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Thanks Lunk.

The Field Museum in Chicago is closest and they will accept specimens for ID, BUT...they want 6-12 months to do so...

I printed out their accceptance form but doubt I will send it in now.It does say on the form to NOT bring the specimen in person as they may not have a qualified person who can look at it right then.

I 'll take the rock to the Lapidary museum in Elmhurst in 3 weeks, see what I can learn...heck, I spent 140 bucks there last visit on Rock ID/fossil books with color plates and a Museum membership. I just couldn't help myself, being in their bookshop 

was like a candy store for adults...

 

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Tom, you might also give this lab a try; they have a very fast turnaround:

New England Meteoritical Services (NEMS) 
P.O. Box 440
Mendon, MA USA 01756
http://www.meteoritetesting.org/

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12 hours ago, tvanwho said:

They are having a meteorite ID class on April 22. I will be sure to attend and take this rock. Heck, I tried to grind off a flat spot on the rock to etch with acid

Sounds like your best bet. You can learn more about how to identify meteorites and get yours identified at the same time. Less than three weeks away.

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DMG Nickel Tests for Meteorites:

SteveH and Lunk reference several sources that give tips on tests for meteorites. One of these is a DMG test for nickel in jewelry. These tests help people who have nickel allergies. On Amazon one DMG test also advertises their product as being useful for meteorites.

Does anyone have experience with these products? 

https://www.amazon.com/Nickel-Meteorite-Testing-Solution-Single/dp/B00K1J9FSI/ref=sr_1_2?ie=UTF8&qid=1492237918&sr=8-2&keywords=nickel+test+kit  

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I used the Nems once and was satisfied with the price and report...well worth the nominal fee, in my opinion.

fred

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