In terms of Prepper stockpiling, I'm not sure that Zinc metal would have the value as a storehouse of wealth, for instance, Aluminum stock, Iron or Steal bars,, Gold, Silver or Platinum.
Aside from it's use in making cells for a battery, I'm not able to think of another use for Zinc metal. Yes, it can be used to coat iron objects, but so can Tin, for the same purpose.
Would you accept Zinc metal in a barter exchange?
Pre-SHTF, Zinc appears to be a "strategic" metal for military and industrial usage. That gives it value while Industries and the military are demanding more production.
I would watch the commodity as an indicator for economic changes.
A question occurs to me: Why did those Zinc mines close?