All of the patches got removed after an update, it seems to be mentioned in the changelog. But on Factoriopedia the only way to obtain zinc chunks is by mining still.

this was an issue i only realised yesterday, you are supposed to get zinc/nickel/iron/copper from chunks now - the only solution i can offer at this exact moment is using https://mods.factorio.com/mod/regenerate-terrain , which might work?
i will release a patch that hopefully fixes the issue and lets old saves be usable with 0.6.500, but if neither of those work then the only other option would be a new save, and i do apologise for the inconveince :]

Ohh, an issue I see. Thanks for the suggestion. I assume that wouldn't work, because I have the ore-ganizer mod and zinc is not one of the options now. blob:https://imgur.com/6b406b0d-7a58-40f8-abe9-a4b9cb296313
Might have to restart oh man ok. Thank you for your time.

Regenerated terrain with that mod and nothing! Oh man.

im currently testing out a possible fix? turns out migrations work differently to what i previously knew, so the next patch should hopefully fix it? i'll message again if it is or isnt fixable :]

its fixable! it'll be in .507 update, just make sure to not save your game/use an autosave if you've loaded in with 0.6.500

Thank you so much! Ohh I suck and it seems I've overwritten both the save and the autosaves, I'll see if I can recover somehow. Thanks for your time and effort.

no problem! i was glad i could even fix it :]