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Hey guys new here and have a question? Hematite? Meteorite?


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I understand what you are saying now Bob and thank you for explaining. I guess I need to learn the difference in what free metallic iron and mineral iron looks like. I have to tell you in my past line of work creditable witnesses are the backbone of any case I ever worked. I cannot dismiss what they saw, with certainty. I know well how witnesses can be mistaken but I personally know all of those involved and to the man I believe what they told me. Too much there to dismiss this as native rocks. I am sure there is an explanation and I hope one day to find it. Bob, can you tell me what difference to look for between metal iron vs mineral iron.Thanks.

 

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That's the right idea, noticing a rock different then the rest, but in general most meteorites will pull towards the magnet, and don't usually find them round. I think you have some native earth rock

Lunk, I tend to agree and without boring you and others during the holidays with the research I have done, I will cut to the chase. I believe the small round concretions that I have are Goethite Concr

There was no sarcasm in my post.  It was negative only in that it wasn't affirmative.

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Mineral iron is sub metallic at best. Like graphite. It is fully oxidized and is not like shiny metal. Magnetite and some hematite will almost look metallic. But it is a bit porous and dull in luster. 

Free metallic iron is metal. Just like a knife blade or an engine block. Shiny and metallic.

Iron from outside our oxygen rich environment is (nearly) always free metallic iron. Shiny and just like smelter iron or steel in appearance.

Iron formed on earth is fully mineralized and (almost) never appears as metal. The only free metal on earth has been smelted and refined.

Take any piece of terrestrial iron and grind it. It will leave a streak of "red" or "grey". Any free metal will streak metallic... It grinds into little metal shavings.

Sometimes the difference can be subtle. But the difference between sub metallic luster and metallic luster is very obvious once you streak a few rocks.

All meteorites do not contain iron. Most but not all. And that iron is always in its free metallic state because it formed in an environment with no oxygen. So it will always look like bright knife steel when viewed in the window you grind in the rock.

If you do find a rock with bits of free metallic iron you have a meteorite or an artifact. If the iron is not free metallic iron you have a terrestrial mineral.

Recognizing the physical and chemical state of iron is the very essence of identifying suspect meteorites. It is often the only test that an individual can perform to separate suspect stones from terrestrial rocks.

That is how magnetism is used. If a stone is attracted to a magnet it contains iron. A quick look at the physical state of the iron attracting the magnet will tell you if there is any possibility it is a meteorite. If the iron is mineral the rock is not a meteorite. If the iron is free metallic iron it does not eliminate the stone. It means the specimen is either man made (an artifact) or a meteorite.

There is a lot of refractory waste (slag) that looks like rock that contains free metallic iron. So that must be ruled out. Slag can often be identified by the abundance of gas bubbles, silica and oxides. Since oxides and gas bubbles do not exist in space it is pretty easy to identify slag. But those identifications really need to be left for the metallurgists.

The basic rule is if you don't see free metallic iron it isn't a meteorite. There are some big caveats there for lunar and martian meteorites that don't contain iron. But if there is iron there it must be in the form of free metallic iron to be a meteorite. If you have iron in the mineral state it is most definitely not of extraterrestrial origin.

There is no doubt in my mind that your people were under a meteoritic fall. They just picked up the wrong rocks. It happens all the time. 

The only way to identify a meteorite is by the presence of free metallic iron, chondrules, and fusion crust. Unless it has one or more it is (generally) not identifiable. A lunar meteorite without fusion crust would be almost impossible for the most experienced hunter to identify because it has no iron nor chondrules. But a stony meteorite is fairly obvious because of the metal flecks and chondrules in the matrix.

An iron rich terrestrial stone is easy to spot and differentiate. The iron is not metallic but rather sub metallic. 

I don't need a magnet or a streak to know your stones have iron in them. I see the analysis report. And since there are no blobs of shiny metal inside I know the iron is in mineral form. Additionally the matrix has no chondrules that you would expect. It is basically homogenous and not granular like a meteorite. Also there are voids in your stone. Meteorites are very dense and do not (usually) have voids. 

An iron meteorite is solid steel. Nothing else. You can't tell an iron from a chunk of railroad track or an old horse shoe from the look of the inside. Your only clue is the shape and look of the surface and that can be very subjective. Even experts argue over certain irons. Since irons are made entirely of stuff that is nearly identical to man made steel and have no chondrules the surface shape and crust may be the only clue for the finder. There are no real tests that can be done except a wiedmanstatten etch to try and get a pattern. That is an iffy thing in a home laboratory and probably best left to an expert.

Some irons are "stony irons" and contain Olivine crystals. Those are generally obviously meteorites. But most irons are "siderites" or pure blobs of metal and you really can't distinguish them from an old chunk of scrap unless they have regmaglypts and fusion crust.

So there is the short course on meteorite ID and how to differentiate terrestrial stones from meteorites. There are some exceptions to some aspects of my little essay and im sure someone will want to argue about some deficiency in my presentation. But generally speaking this is a good basic knowledge of what to look for.

Hope it helps!

 

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The type of test you got showed elements. Not compounds. You see iron in there but the test gives no inkling about what chemical state the iron is in. 

There are several types of materials analysis. Each has its own strengths and weaknesses. For each type of test you can draw conclusions and are free to make assumptions but you run the risk of those assumptions being incorrect.

There is iron in your stones. That is a safe conclusion. The assumption that the iron is in the same chemical state as meteoritic iron is incorrect. The type of test that was done identified elements. Not compounds. And therein lies the problem.

That is why it takes an expert to interpret test results. Laymen make incorrect assumptions. It is easy to know just enough info to fool yourself when looking at an analysis.

I am no expert on anything. Therefore I make very few assumptions. I must strictly adhere to what is known lest I come to an incorrect conclusion. I know how to do field tests for iron and not much more. In this particular case that was all that was needed.

Merry Christmas.

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Bob, thanks again. I wish I knew enough about geology to make assumptions. I can only go by the test results and as you pointed out, I need additional testing. I have learned that even the experts don't always agree. I really do rely a lot on the testimony of my friends here in Louisiana. I know, they could be mistaken. I am only one of two who collected any of the rocks found. Of the other three, one is a minister, one is a banker/farmer and the other is a federal judge. I have decided to take your advice and try to get this to a lab for further analysis. If it weren't for what they saw and know I would put it to bed.

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I took Bedrock Bob's advice and did a streak test on three different rock samples I picked up from a reported witnessed fall. Each sample rock gave a different result. The light-colored rock seen here on my kitchen island did not leave a streak at all. The larger dark rock left a reddish-brown streak while the smaller round rock left a black streak. None of these rocks are attracted to an earth magnet. Tomorrow I will try to post better pictures along with the streak marks to each sample.100_0947.JPG122310 (15).JPG20160121_130350.jpg

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