alison sent me the wikipedia article for hot-dip galvanization (https://en.m.wikipedia.org/wiki/Hot-dip_galvanization), or the process of coating iron or steel in zinc to form ZnCO3 (zinc carbonate) to prevent rusting. it forms an easily recognizable spangled pattern which immediately caught my attention as it looks crystalline! after talking to my dad (a geochemistry professor) i discovered that the formation of the spangled pattern is a matter of grain boundary energies (https://en.m.wikipedia.org/wiki/Grain_boundary), where each crystal attempts to minimize boundary energy as it grows, resulting in the shape characteristic of the crystal (when other crystals don’t prevent that shape from forming). this made it clear that a specific mineral is resulting from the galvanization process: smithsonite! (https://www.mindat.org/min-3688.html) essentially, this mineral doesn’t have time to grow thick, so it creates a thin, rust-resistant coat; but as it grows, it leaves behind the pattern typical of hot-dip galvanization.

 
this is a sample of azurite i packed at work today that really caught my eye. this mineral has been used in pigment for centuries and it’s easy to see why