TIL my vinegar test on a 'gold' nugget from the creek gave me a surprise

I was cleaning up some creek finds from a trip to the Blue Ridge foothills and had this one piece that looked like a small, rough gold nugget. I've always heard that a drop of white vinegar can help tell gold from pyrite, since pyrite will fizz. I put a drop on it and waited. No fizz at all, which got me excited. But then, after about a minute, the spot under the vinegar turned a dull, chalky white. That's not right for gold either. I looked it up and it turns out it was probably a piece of weathered galena, and the vinegar reacted with the lead to make lead carbonate. I thought the test was a simple yes or no, but it showed me there's a whole middle ground of weird mineral reactions. Has anyone else had a common field test backfire and show you something totally different?

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spencer_chen66mo ago

That "whole middle ground of weird mineral reactions" reminds me of the time I tried the magnet test on a rock that just stuck to everything.

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verap525mo ago

Had a rock once that stuck to a magnet so hard I couldn't pull it off without prying it, thought I'd found a meteorite or something. Turned out it was just some old slag, but it definitely made me feel like a rock genius for about five minutes, @spencer_chen6. Funny how those tests make you question everything you thought you knew.

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mason8476mo ago

Oh man, that's wild! I had a similar thing happen with the old "streak test" on a piece of shale. I was sure it was coal, but the streak came out this rusty red color instead of black. Totally threw me, and it turned out to be some kind of iron-stained something-or-other. These quick tests are handy until they open up a whole new can of worms.

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