Pan Question? Is this rust or niter deposits?

[Ausable]

On damage to pans. Years ago - I had a large aluminum pot I used to finish syrup in and it worked just fine. At the end of the season on finishing my last batch of maple syrup - I tossed a dirty filter into the aluminum pot with the intention of cleaning both as soon as I cleaned some other things and put it up on a shelf. Wrong thing to do - I thought I had everything cleaned and put away. At the start of the next season - I lifted the pot down and then the light came on - Oh No! - The maple sugar in the dirty filter had a chemical reaction with the aluminum and had eaten a large hole in the bottom of my favorite pot. So - like Dr. Tim points out - we have to pay attention to business. -----Mike-----