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Help Identifying Mystery Rock / Metal

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I was out detecting with my Equinox and had a solid 21-22 on the VDI numbers, it never flicked off those numbers, it was down about 15 cm's.  I dug it up expecting a NZ $1 or $2 coin, both come up the same numbers.

I was puzzled when what I ended up finding was a rock looking object

This is it next to an older NZ 10c coin I found only minutes before hand

10cent.thumb.jpg.32a934eec6377d3593b30eac31a970e0.jpg

To me it looks more like a rock than a bit of metal, I tried to hit it as hard as I could with a hammer to see if it was a chunk of lead or something thinking that would flatten it, it didn't make a mark on it. I then hit it with the back flat end of my Log splitter thinking this will surely do some damage to it, but no, it didn't leave a mark, all it did is cracked the concrete under the mystery object.  This thing is extremely tough.

It weighs 17 grams and feels quite heavy for it's size and not magnetic.

What could it possibly be? 

rock2.jpg.731ee994d8587d35e335a36068391f58.jpg

 

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Maybe a specific gravity test might reveal what it is

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20 hours ago, normmcq said:

Maybe a specific gravity test might reveal what it is

That's a good start.  If it's 10 or higher you really narrow down the possibilities.  There are zillions of metals in the 7-9 range and Murphy's Law says it will be in that range.

 

Also, 'cutting' a small groove with a triangular file might show the untarnished color of the natural metal.  It's easy to identify copper (possibly not pure but alloyed) that way.

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Look up the mohs hardness scale and run some of those tests to determine its hardness, then look up streak testing and perform that (for streak testing you will need a white un glazed piece of ceramic, or black depending on the color of the streak).  

With its hardness and streak known as well as some of its other attributes you should be able to narrow it down.  

 

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That is a weird one Simon. I can't see how any natural "rock" would not have shattered under the abuse you gave it. (How hard did you hit it?:biggrin:)  But the concrete under it did.:ohmy:  Bugger. Hope wifey did not growl at you.:laugh:. It obviously has metal in it or it is all some kind of metal. I doubt very much it is of a natural occurrence especially from your locality. Man made perhaps. Tungsten?? Seems pretty tough, unless you just really gave it a girls hit/tap. :laugh:

JW :smile: 

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3 hours ago, kiwijw said:

It obviously has metal in it or it is all some kind of metal. I doubt very much it is of a natural occurrence especially from your locality. Man made perhaps. Tungsten?? Seems pretty tough....

I thought of tungsten, too.  Density test will sort that in/out since tungsten specific gravity is close to gold.  It's the only affordable metal that is up there (specific gravity, that is) with the valuable gold and platinum group metals.  I've wondered if it would be a good practice metal for gold panning, sluicing, etc. but I've never read it being used for that.  Hard?  About as hard a metal as you can find.

But what is a chunk of tungsten like that doing there??

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6 hours ago, GB_Amateur said:

I thought of tungsten, too.  Density test will sort that in/out since tungsten specific gravity is close to gold.  It's the only affordable metal that is up there (specific gravity, that is) with the valuable gold and platinum group metals.  I've wondered if it would be a good practice metal for gold panning, sluicing, etc. but I've never read it being used for that.  Hard?  About as hard a metal as you can find.

But what is a chunk of tungsten like that doing there??

I have no idea, it's an unusual shape too, it looks natural.  

I'm going to do all the tests on it, hopefully tomorrow if I can get the time, lifes been busy the past week, Jim Hemmingway sent me a good field guide that will help with that also. I'm just interested to see what it is, I know its not of any value but its the mystery that has me.

We had visitors today and the guy was baffled by it and was surprised how heavy it is for the size of it, he thought it looked natural too.

I was showing him how hard it is and I had a stainless steel nail and got him to hit the nail into it, the nail had no hope.

On the smooth spots it reflects light.

I did get growled at as it was our path 🙂, I seem to get in trouble a lot lately... this new hobby of mine is a trouble maker 😄  I hit it with a log splitter, even a girl can do damage with that thing!!!

The gold chance indicator on the Gold Monster 1000 slams right over to positive.  I know it's not gold but that means its a strong non-ferrous I guess.

I think it's tungsten as a guess, I found this article which indicates tungsten maybe found in my area

https://www.stuff.co.nz/southland-times/news/104465700/potential-for-rare-earth-minerals-in-southland

 

 

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I managed to clean up my metal rock a bit using an angle grinder, it becomes a nice silver colour after doing that, also, I did a very basic specific gravity test on it and it came out at 19.12

20180821_124624.jpg.b997a8532e8380423ed998e59fa6261b.jpg

The grinder didn't change the shape of it but it cleaned the outer layer of dark stuff off

 

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A specific gravity of 19 would suggest tungsten but naturally occurring pure tungsten is often brittle. Single crystal tungsten would be hard but rare. Tungsten carbide would have the hardness but a lower specific gravity. An x-ray fluorescence test will give you the answer.

Here is a map of tungsten locations in NZ:

 

40F38330-08FF-461F-849C-D4AE1F92B425.png

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