Fools Gold
It didn't fool me, but I can see how it would fool someone and I did have to test it just to make sure.
I was putting some more rocks around our pond this morning. Remember the ones we moved at my in-law's place yesterday?
Well we brought some of them back to fill a few spaces.
Anyway, while re-arranging some of the rocks that were already there, I noticed one that was literally sparkling in the sunlight.
Out came the geologist's hammer, the hand lense, the pocket knife and a couple of geology books.
My first thought was that it was Mica, but looking at it through the lense it wasn't that. It scratched the side of the pocket knife, so it was too hard for either Mica or Gold. That left Pyrite, or Fools Gold, and a fine example of it too.
The picture here is a small part of the original rock that I broke off with the hammer. The original was about the size of my hand. The picture doesn't really do it justice, in the full sun it really sparkles. There are small seams of Quartz through it as well. Gold is usually found with Quartz, so that added to the thought that it might have been Gold. 
2 comments:
Well it's hard to see in the pictures, but it doesn't look like they have the cubic or pyriteohedron form http://en.wikipedia.org/wiki/Pyrite (But I may be wrong, because I can't see the picture that well, good old rocks are hard to photograph well).
The other one it could be is chalcopyrite: http://en.wikipedia.org/wiki/Chalcopyrite .
Also pyrite and chalcopyrite have a dark greeny to black streak (colour of powdered mineral) whereas, gold is the same colour as it's actual colour.
I'm almost certain you're right Matt. The crystal structure points more to Chalcopyrite than Pyrite.
I'll have to wack a macro lense on the old Olympus and drag the studio flash out to get a decent pic. Those new fangled, digital SLRs have their limitations after all.
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