Warning: My calcite sample took two months to clean because I used the wrong acid.

I found a nice piece of calcite in a Missouri creek bed, but it was coated in iron oxide. I tried a weak vinegar soak for a few days, which did nothing, so I jumped to muriatic acid and it started to eat the crystal faces. I had to stop and slowly neutralize everything, then go back to a much longer citric acid bath. What's the safest way you've found to clean iron stains off calcite without damaging it?

2 comments

2 Comments

parkerb6516d ago

My own Arkansas calcite was ruined by a ten-minute phosphoric acid dip.

ben40216d agoMost Upvoted

Oh man, @parkerb65, that's a tough lesson to learn the hard way! Phosphoric acid is no joke on calcite, it eats right through it. Ten minutes is basically a death sentence for a specimen like that. Always gotta test on a tiny chip first, no matter what the internet says. Really feels bad when a good piece gets turned to mush. Your poor Arkansas calcite didn't stand a chance!