I changed the battery in my 2005 Volvo S80 back in August 2016. There was an old Genuine Volvo battery with a sticker date of 08/2006 that was removed. The battery posts and cable clamp were in pristine condition. I replaced it with a
EverStart Maxx Lead Acid Automotive Battery, Group Size H8 and when I inspected the battery back in November 2017 I found a ton of corrosion on the post and terminal clamp.
What exactly is this material at a chemical level? I can see that the terminal clamp's metallic plating had dissolved off to reveal the underlying copper, and I'm guessing that Cu atoms got into the mix somehow to cause the light blue shade in the forming crystals seen in the images below.
Where did all this matter come from? Did my battery leak some kind of liquid that evaporated and left behind these salts, or was water taken out the atmosphere? What's going on here at a chemical reaction level?