I don't know myself, unless you could use thinset mortar, My friend who is a stone mason, gave me a few tubes of silicone adhesive he uses for applying cultured (Fake) stones to the sides of homes, and I'm going to try using that on a broken bunny ear, so I'll let you know how it works out. I too have a bird bath I'd like to repair, it's very art deco and I was thinking of using thin set mortar on it, and I want to use these 70's 2" tiles on it but have been procrastinating on how to prpare it(clean it)