What is the green mineral collected around the hot-water valve of my bathroom sink?
This mineral has formed in a crystalline structure on the outside (not in a problematic way) around the valve for hot water, but not cold. I think this has something to do with galvanization and specifically could involve a reaction with zinc oxide. So what is this and why is it only on the hot water side?
(Note: It comes off very easily, is not a hazard, water is clean by virtue of a city water-treatment plant.)