Someone gave me some rocks but there were invasive vines on them that they tried to burn to kill. The rocks now have black charred places on them. I tried just plain water of course, but that would be too easy... I thought of vinegar? baking soda? or? I don't want to do anything too drastic and take off the patina/color of the rock (it isnt burned all over, just patchy) and some of the rocks have lichens on them that look like they could still be alive. Anyone with ideas?
