Popcorn Rocks

When dark limestone (calcium carbonate) or dolomite (calcium magnesium carbonate) is barely submerged in vinegar (acetic acid solution) and the vinegar is allowed to slowly evaporate to dryness, white popcorn-looking crystals (calcium acetate?) grow on the surface of the rock. I have seen these rocks for sale in stores; I found mine in a park. I have seen an article (in the Journal of Chemical Education?) describing the chemistry of this process. If anyone knows the reference could you please let me know?

 

BELOW: Popcorn rock surfaces without (LEFT) and with (RIGHT) "popcorn" crystals.