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How can I get a solid chunk of Pyrite / Fool's Gold? Answered

I am currently in need of some Pyrite, but in the amount of at least 1cm sq. It is in the river system everywhere locally, but only as very small sparkles, I have never seen a large rock of it. Does anyone know if I can smelt it into a larger block? Does it have any special properties that I don't know of? ( Is it magnetic for example )

I could buy it from the gem store, but this will defeat the purpose of the project.
Thank you for you help :D

9 Replies

Jack A Lopez (author)2012-10-11

Making large single crystals of synthetic iron pyrite would indeed be a neat trick.

This page gives sort of an overview of different methods for growing synthetic crystals

One of those methods is slow cooling of a liquid. The Czochralski method (http://en.wikipedia.org/wiki/Czochralski_process)is well known example of these. It is well known since it is used for making large single crystals of pure silicon, which are cut into wafers for making computer chips.

An overview of several of these slow cooling of a liquid methods (Verneuil Method, Czochralski Method, Bridgman Method, Kyropulos Method, Bagdasarov Method, and a few others) can be found here:

The trouble with iron pyrite though, is that I don't think it is going to melt at ordinary pressures. The Wikipedia article on "Pyrite",
(http://en.wikipedia.org/wiki/Pyrite) in the "Uses" section there is a paragraph that says  Pyrite decomposes at around 550 C.

"Thermal decomposition of pyrite into FeS (iron(II) sulfide) and elemental sulfur starts at 550 °C; at around 700 °C pS2 is about 1 atm."

The reaction for that is:

FeS2(s) = FeS(s) + S(g)

So I am guessing  a very high pressure (of sulfur gas) would be needed to push that equilibrium back towards the left.  Also guessing that such conditions exist deep underground, and that's how natural iron pyrite forms.

I don't know what you'd need to do to make this happen in the lab.

I'm not saying it is impossible, just that I think making large crystals of iron pyrite using one of the melt-with-slow-cooling methods, is going to be tricky.

Of course there were other tricks that I don't know much about either,  like that vapor transport, or vapor deposition mentioned in the first link. 

If you could figure out how to grow thin films of iron pyrite, maybe you could sort of make a fake big crystal by growing a thin layer of pyrite on a cube shaped substrate made of something else?

Like they do with those titanium nitride coated drill bits,
Coincidentally, that TiN stuff kind of looks like gold too.

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AtomRat (author)Jack A Lopez2012-10-11

This is possibly more the way I had been looking into. All techniques seem interesting. I will need to read more into this, but thanks for the answer, it may be my only hope.

There is an issue, I do not know if synthetically it would still work the same as a natural occuring cube. It may loose its electrical properties. Thanks for the answer

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Jack A Lopez (author)AtomRat2012-10-11

I wrote kind of a long answer just because this seems like a very interesting question. It got me wondering: Is there a way to make large crystals of iron pyrite?  I mean there are ways to make large synthetic diamonds, so there probably is a way to make pyrite.

A shorter answer is that I think the equipment and time required to do this would be much more expensive than just buying a chunk of pyrite, from somebody on eBay, or wherever else rocks like this are sold. 

I have not seen a lot of pyrite where I live, but apparently in some places it is common like dirt, or like you were saying, like river sand.

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Re-designBest Answer (author)2012-10-10

I doubt that you can smelt it. It grows naturally as a crystal. You can use is as a detector in a crystal radio. Do some digging if that's allowed and you might find some larger pieces. 1cm is not a very large piece.

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AtomRat (author)Re-design2012-10-11

Sure digging is allowed, this stuff is in our river beds here almost 50% sand , 50% fool's gold "dust" or glitter. I will still attempt to find it this way. I'd better do some research now on how far I might have to dig and where.

You are spot on for the "use of a detector", this is the exact reason I want it, ( making a radio from scratch, instructible in the making now, 80% complete-ish )

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Re-design (author)AtomRat2012-10-11

if it's that common, then you ought to be panning for gold since they are often found in the same locations. Find some gold, sell some gold then you can buy a nice chunk of pyrite.

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frollard (author)Re-design2012-10-10


"is there anything (author) doesn't know?"

...not sure. When in doubt look it up :)


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canucksgirl (author)2012-10-11

We have a rock sample here (somewhere) with a large number of iron pyrite "cubes", probably in the 1cm range... If you don't need it right away, PM me your address, and I'll see if I can find it and just mail you a piece. (Even to Australia, it shouldn't cost much to send)...

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AtomRat (author)canucksgirl2012-10-11

That would be amazingly great! Thank you very much! I dont think that I would find a cube if I looked anyway, and if it has some nice straight edges on it, it would be perfect. It is for use in an attempt to make a piezo from it.

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