How to clean my new rock walls...
I purchased a house last October and am finally getting out to spruce it up a bit. There are very old rock walls, which are really cool, but in addition to the moss overtaking them, there is a white (very hard)scaly substance on them. I have tried wiping it and scraping it off with garden tools and it barely budges. Not sure if it is some sort of calcium deposit or what. I have included a picture. Thank you for any advice in removing the substance!
Here is a link that might be useful: