Distinguish Two Pieces Of Mineral Magnetite As To Source

XRay diffractometry?

https://www.rigaku.com/en/products/xrd/smartlab/app028

I was thinking XRD, or maybe XRF (X-Ray Fluorescence).

Maybe, I will not comment on my chosen technique yet.

This tells me that you have too much time on your hands.

Basically, it came up in conversation with wifey, during the program. They said the pieces in question came from Arkansas, about 1800 B.C.

The usual disagreement came over where the native Americans could have done the fine work on the plumb bob, and I said yes, and she said no. She said others must have brought it here, and I don't her, do not discount the Choctaws of Northern Louisiana (Arkansas).

Keep guessing how to analyze and tell the difference. I will reveal my take on it later.

I'm going out on a limb here...

Perhaps in chipping away at a piece of magnetite, the vibration might cause the magnetite to become magnetized by the earth's magnetic field. If the plumb bob (or arrow head) were chipped away pointy end down, the vertical component angle would be stored in the piece of magnetite. There would be little difference in locations a few miles apart, but there could be a lot of difference in different parts of the earth.

http://srjcstaff.santarosa.edu/~lwillia2/42/42Labmagprelab.pdf

This might be a valid answer, but suppose the two objects are considered to be ancient, at least 3000-4000 years age since mined. Orientation would be very hard to verify.

I will provide my suggested answer today, some time.

I have not seen the program so cannot comment directly but I can debunk some myths. With respect to your wife, her assertion that the items had been transported to the site leave open the questions of why and by whom. The earliest recorded mention of magnetite was by the Greek philosopher Thales of Miletus in the 6th century BC but he refers to local deposits from Mount Ida in Greece. He noted that two pieces attract/repel each other and affect iron. He offers no useful application, The first recorded mention of it's use as a compass was by Shen Kuo in China who wrote about it in 1088 AD. The Norse Sagas refer to a "leider-stein" in about 1180 AD and this date ties in with the Viking colonisation of Greenland circa 980 AD. The common name of "lodestone" is Anglo Saxon and translates literally as "Leading Stone" Once their use as a compass was established lodestones were much prised and exchanged hands for very high prices. This is the first indication that they were traded and travelled long distances from where they are found naturally.

Given that these samples are dated as 1800 BC it seems unlikely that they served a useful function but they would probably have been used by a shaman, an old name for a healer/soothsayer. One stone in isolation has no obvious special properties which explains why two were found together as both are needed to observe attraction/repulsion. This also means that both stones must have come from the same source. The plumb bob shape would allow them to be suspended to demonstrate their properties, I would speculate in a ritual or soothsaying context. Both strings of equal length the stones would repel. One sting slightly longer than the other the stones would attract. A great way for a shaman to get his preferred outcome. That would also explain why so much trouble had been taken to shape them.

The magnetic effects in magnetite and all other magnets decay approximately exponentially over time if a "keeper" is not used. When first observed these 3800 year old stones would display much more pronounced repulsion/attraction.

I would just take it to these guys....

https://www.mindat.org/min-2538.html

...because I wouldn't know shit from shinola....

You can usually tell by the smell.

I'd NOT use the taste test. Onlookers might not understand.

I'll have to take your word for it...

3. Iron age. Group travel from European continent to Iceland, like the Vikings. Groups that created items from iron ore traded with other local groups.

I agree with Rixter for the technology to use.

I'm guessing one of the two items was made from meteorite iron.

Go back and RTFQ. I said already that both pieces are magnatite. Now let's just say, both pieces are plumb bobs, with a nice roundness, coned tip at bottom, and a string eyelet at the top.

I have read it multiple times, and it seems like the more I read it, the less I know about what you are asking.

It is not unusual for non-geologists to refer to any magnetic mineral as "magnetite". I suspected you were referring to the relatively recent discovery that King Tut's dagger was made of meteorite iron.

Then the last two statements, which I thought were supposed to be clues to the location, may have thrown me off, as I don't know where two continents on opposite sides of an ocean are only 20 feet apart...

"... I don't know where two continents on opposite sides of an ocean are only 20 feet apart....."

just a guess here...perhaps those two contenents could have be found forming 20 feet apart on opposite sides of the Panthalassan Ocean or Mirovoi Ocean, during the breakup of Pangaea or Rodinia, respectively.

...sorry, I don't know the names of the oceans that surrounded the other supercontenents, like Columbia, Pannotia, Gondwanda, etc.

I am not referring to meteoritic iron. I am referring to magnetite, Fe₃O₄ iron oxide, the magnetic oxide that is black.

Consider that the two pieces might be from one identical (the same) source, as in 20 feet apart, or may be from different sides of the ocean, (Atlantic), and distinguishable somehow, or not, depending on impurities present.

These have already been classified as within the same time period of origin.

The ax head I saw, appeared to be not all that sharp, but had evidence of being sharpened before. It is more narrow at the top except for the reduced diameter ring around it for handle tying. Basic geometry is a hatchet, but is almost a blunt instrument of attack, not what I would call a good wood ax. It would have made a formidable weapon on a medium length shaft.

Let's dispense with the ax head now, and for the sake of this thread, say we have two plumb bobs, and want to know if from same location source, or just one if you prefer, and all the reference data we need. And we can write off and have more reference samples sent as required of raw magnetite from the areas in question.

First: look at the reference data to see what techniques were used, and how easily different sources can be discriminated.

Depending on what techniques were used to produce the reference data sets, you may opt to stop right there, and have this same analysis done on the unknowns.

If they do not match each other (within limits), and the reference samples provide matches (within limits), then you have a preliminary answer with caution. One still needs to review the statistics of the global mapping of trace minerals extant in magnetite from various sources to ensure validity in declaring a distinction.

If no declaration can be made between reference sets of data, then you must opt for some other technique, that might reveal more, or better precision of trace elements not picked up by the first sets of data.

I will hold my beans on my answer for another little while.

I wasn't very interested in material science when I should have been but I would expect trace elements would be the tell tale indicator of where it came from.

Does your answer involve geometric crystal shape? Lastly, does the cost of the single technique factor into your question?

Crystal shape may or may not play a role, especially if some odd or unusual physical method is used, such as trying to make an oscillator crystal from the specimens.

The cost is not being considered to be a factor, and the answer I have in mind is totally out of the scope of most laboratories.

"The cost is not being considered to be a factor, and the answer I have in mind is totally out of the scope of most laboratories."

In other words it's a government job!

The Internet! Magnet Cove, Arkansas

http://rockhoundingar.com/magcove.php

Interesting and varied minerals may be found there, including magnetite. Union Carbide did some mining there, I don't know if they still do.

Certainly, an interesting place on the map, geologically speaking, and otherwise, of course.

Don't read too much into it on #3 question: If within 20 miles, I suggest that no analysis may be available to distinguish clearly, although it might, depending on geological event related to bringing material to/near the surface, and the time the geological events took place.

Otherwise you are pretty much dead on. I will spill my beans on this later today.

I'd ask these guys for some help with tracing the minerals to its origin.

1. Maybe if the probes have a traceable metal content

2. It works for Gold, why not for Magnetite

3. Forming and not chemically changing the mineral should preserve the ability to trace the mineral, the difference of 20 miles or across the ocean will be as big as the difference in the chemical content.

What does this tell you, if the sites were on either side of an ocean? What does it tell you if the sites were within 20 miles of each other?

The only place I can think of that both of these could be true would be the Bering Strait, North America and Asia.

https://en.wikipedia.org/wiki/Bering_Strait_crossing

Still reading too much into it, I think. It is not an and question, more of an either or.

So whats your solution? Now that the thread disappeared from the front view you might as well solve it!

I don't know the answer; but why a 'plum-bob' which suggests an advancement in civilisation for upright vertical structures - or the shape is of something primitive like a piece of jewelry hanging around the neck like a pendant.

Also I am not sure why the need to know - what is to be proved by the answer - ethnic origins of the 'owner' - the source of a valuable mineral - ?? just curious.

Well, here are the beans:

(1)The preferred technique to distinguish the origin of two samples of magnetite (one a plumb bob, finely crafted, very round axially, fine cone point, narrow hole at top for suspension, the other a more or less rough stone ax head), would be the most sensitive isotopic analysis possible, and would more than likely require neutron activation of sampled material. This requires exposure to a hot neutron source (in some sort of nuclear reactor). The counts and energies of all radiations are then determined using the most sensitive energy discrimination available. Alternatively, a lower cost method utilizing laser-induced breakdown a few layers past surface might work nearly as well to reveal trace mineral content, and also some isotopic content present if sufficient wavelength resolution is available, although I would not count on it. Advanced techniques using mass spectrometers may also reveal the trace composition, and native isotopic composition.

NEUTRON ACTIVATION will be preferred, as this has been done and is very sensitive to isotopic and trace elemental content.

(2) It is my opinion that since the two samples could have been formed by different or the same geological events, if they originated on opposite sides of the Atlantic Ocean (as if Vikings brought the plumb bob over), it should be possible to distinguish sources, given sufficient numbers and sites sampled for the exemplars of European origin. This is not to say China is ruled out, so we might even analyze samples known to China as well, especially if no "match" occurs at first.

(3) If the site origin of the ax and plumb bob are: plumb bob from Europe, and ax head from America, then we have a hint that travelers from Europe were here very early, who knows, maybe there was also an Atlantic ice bridge(???), depending on geological age, and weathering of the exemplars found as implements.

If not distinguishable, or apparently originating within 20 miles yet distinguishable (and the source is clearly American), then we know that indigenous peoples were capable of producing both implements and therefore highly skilled in stone working.

If the source is clearly European on both, then we have quite another answer indeed, and it does suggest trans-oceanic trade existed, or that stragglers came over, and contributed whatever, then perished, etc.

Then the mention of magnetite had absolutely nothing to do with the question. The two objects could just as well have been fabricated from black obsidian, or black chert, etc.

No, they are real objects (as seen on TV), and were identified clearly as magnetite.

Yes, one could attempt several different physical analyses also, but these might not be quite as discriminatory in results.

Hardness, color, streak test, magnetization curve (somehow normalized to volume of object and topography I guess), electrical conductance, magnetization decay time constant, magnetization orientation compared to any grain structure evident.

I cannot think of other possibilities right now.

So I was on the right track #18

Interesting!

Yes you were, IMHO!

Well don't you think that deserves a GA?

Oops, apparently, I neglected to provide you with a GA on that. You now have two.