Zinc protects other metals from rust, so it is read as quiet protection and support in the background. It can point to someone, perhaps you, shielding others without being noticed.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.