Where to find Valheim iron, and all crafting recipes

So, you've swapped out your rags for troll tunics, your stone axe for a shiny bronze one, and put all that fine wood to good use to make a fancy bow. Now you're wondering what's next? Sweet, sweet iron, my friend. By now you probably have a blast furnace and a forge, and have been smelting down the copper and tin deposits you've found around Black Forests, Meadows, and the shoreline. If not, do this first so you can make bronze Valheim weapons, as well as new armour, and bronze nails to craft a much better boat than the rickety wooden raft a sea serpent inevitably ate. Many materials are locked behind Valheim's progression system, and you need to defeat bosses one by one to open up better tools. Without the antler pick axe from the first boss, you can't mine copper or tin to build better bronze gear, or a build cauldron to create mead recipes for battles. It's almost impossible to skip this step and go straight to iron, so have patience. Here's exactly how you acquire iron in Valheim and everything you can craft once it's yours.