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G,day Mike . Iron pyrite is a type of iron sulphide  , it has a crystalline structure that is usually brassy or gold in appearance . Pyrite or "fools gold" is often seen in the alluvials in creeks and streams and due to its shine and light reflective qualities is mistaken by prospecting newbies as gold . A metal detector would "see" iron sulphides as background mineralisation due to the fact that it is rarely found in large lumps but rather broken and scattered in sand particles although at times crystals can be found in quartz and ironstone in bulk deposits . As gold deposits in Australia are usually associated with iron of some description we are constantly battling this presence in an effort to find the gold hidden within . Articles written in this forum will give you a good idea on the brands available and the various models ability to handle the effect of ground mineralisation . 

Regards PM

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Fools gold is a class of items that fool people into thinking they are gold. Also, they really don’t look much like gold so you really do have to fool yourself into thinking it is gold.

Pure pyrite is iron sulphide and it’s structure makes it non-magnetic and so minimally conductive that a metal detector will not sound off on it at all. It is usually other sulphide in the mix that sound off. Arsenopyrite is highly conductive, but it looks even less like gold than pyrite. Most pyrites have a blocky, hackly type sharp edge appearance that does not look like gold since natural gold rarely has sharp edges and straight lines.

The most common fools gold in my experience is mica flake. Mica acts like little mirrors and reflect golden sunlight. This is the stuff in granitic rocks that flashes like gold when turned in the sun. If you look in water and see gold flashing on a sand bar, it is probably mica flake. Mica is very light and tends to float on top of sand and gravel. That’s clue number one it’s not gold, which would sink. And it only look like gold when the light reflects just right, otherwise it does not look like gold at all. Very easy to flake apart with a steel pin.

The bottom line is once you get familiar with real gold then fools gold does not fool you anymore and it becomes a non-issue. The only “fools gold” that has me guessing sometimes is a bit of discolored mineral so small I need a hand lens to see it in quartz and I might have to mull a bit whether it is a tiny bit of gold or something else. Usually the fact I have to even think about it means it’s not gold.

When I owned a shop I had countless people bring in fools gold. Most was mica they had laboriously panned. Almost nobody ever brought in real gold. When you find real gold there rarely is much question about it.

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I

2 hours ago, 57buick said:

And when you find large pieces of pyrite, at least here in Oregon you'll notice amazing perfectly formed cubes. Almost looks man-made lol

I was really surprised. I thought it small and glistened. Did not know about the cubes.

image.gif.7c237f42cec29c3bf6c0b7fe94358157.gif

Beautiful crystal formation. Nature is really fascinating.

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Here's a question for Steve . If iron pyrite is paramagnetic does this mean it could cause an effect on an induced magnetic field in the same way as permanent ferromagnetic mineral Even if it's only short term whilst it's in the coils influence.

regards PM

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Good enough for me , ive never found it in large enough quantities to test not that I've ever had the urge to,  I'm still trying to work out why my GM picks up my hand , it makes it almost compulsory to use a plastic scoop. The metal detectors we have at work for food packaging screening certainly will pick up your hand although the coil is a square unit that's about 4 foot square and must have very high sensitivity as they have to find tiny metallic particles inside 20 kg bags of flour based products.

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