I'm not sure if this works for salamanders, but if you put a drop or two of vinegar on the rock and nothing happens then it is supposed to be aquarium safe. If it fizzes it's probably a no go.
I'm not sure if this works for salamanders, but if you put a drop or two of vinegar on the rock and nothing happens then it is supposed to be aquarium safe. If it fizzes it's probably a no go.
Almost all rocks which normally used in aquaria/terraria are on the unsafe-list. I wouldn't bother much about this. If rocks were unsafe, there wasn't any life on this planet anymore.
Joost is 100% right. Rocks are composed of an array of different minerals. Those rocks shown look perfectly safe to me even if they are limestone.