What Happens When You Leave Limestone In A Vinegar Bath For A Week

[Mediospirifer]

A week ago, on Thursday, I set some chunks of limestone in a vinegar bath to extract microfossils. Since my vinegar supply was low, I only filled the tubs halfway, and I left the lids off. My plan at the time was to return in a couple of days to filter the liquid, but life intervened, and by the time I could do something else with them, they were growing some rather pretty crystals!

I decided to leave them alone and see what developed. Here's what they look like today:

I think this one looks like caulifower:

And this like a leafless forest:

Unfortunately, the "cauliflower" fell off the rock after I took the picture, and some of the "trees" are falling down (which is why I decided to photo it today!), so it's probably time to decide whether to continue processing or try to preserve them as they are. I don't know whether these crystals will persist in the absence of a calcium carbonate-enriched solution or not.

Just thought I'd share my unplanned chemistry experiment!

[vertman]

Very cool!

[Foshunter]

I like it----Tom

[MarcoSr]

Really neat! I've processed a lot of limestone in vinegar and have never grown any crystals. But I have always completely covered the limestone with the vinegar.

Marco Sr.

[JimB88]

Ive had that happen too. Remember, unless the fossils are silicified, they will dissolve too.

[RyanNREMTP]

Purdy.

[Mediospirifer]

Really neat! I've processed a lot of limestone in vinegar and have never grown any crystals. But I have always completely covered the limestone with the vinegar.

Marco Sr.

Likewise. I've had calcite deposits around the rim of the tub, and seen some frostlike patterns develop on the bottom of a tub that was left standing with a little post-dissolution vinegar in it, but this is a first!

What's particularly curious about this is that all of the crystals have grown on areas that are well above the level of the vinegar, and the rock appears wet all over, despite standing exposed to the air for several days. There's something going on here that I don't fully understand!

Ive had that happen too. Remember, unless the fossils are silicified, they will dissolve too.

Or phosphatized. The conodonts I've extracted from North Evans limestone have been fairly resistant to the etching of the vinegar as long as there's still limestone matrix present for the acid to work on. Calcified fossils are certainly vulnerable.

[Coco]

I have often had this problem when I cleaned my "Falun" teeth. "Falun" is a Miocene calcareous sand. If we put the falun in some vinegar and it evaporates, it trains "cauliflowers" (I also call them like that !) as yours. Then it is necessary to soak for a long time by changing regularly the water to remove any track of vinegar which can damage some fossils.

Coco

[JohnBrian]

Neat!

[MarcoSr]

I think that the porous limestone is wicking the vinegar to the surface, where it is evaporating, like Coco pointed out,building your crystals.

Marco Sr.

[creto]

This has happened to me once- only I forgot them for much longer. All the vinegar had evaporated and the results were fantastic. The crystals were very, very fragile. I think I have seen at the rock shop a kit with a similar reaction with vinegar that advertised "crystal gardens". If you want to dissolve limestone or any calcareous rock the vinegar should be changed as soon as the fizzing stops- no more than a couple of days.