Damn.
I just spent a good 4 hours or so inside this massive cave network. I found my first gold, my first redstone, and my first diamonds. I also created a bunch of obsidian blocks when I accidentally diverted a river into lava, but I couldn't figure out how to harvest the ore without it just falling into the lava below. I made 3 (or was it 4?) "camps" in the cave with a workbench, furnace, and chest: one just inside the entrance, one at the very bottom by the lava, and one or two partway down. I ran into a lot of monsters in the bottom area, and although I killed most of them, an archer and a zombie managed to finish me off. Fortunately, all the valuable ores and even the diamond pickaxe are safely inside chests. The most valuable things I dropped were my iron armor and the bow and arrows. Everything but the arrows is easy to replace, so I don't think I'm even going to try running down there to retrieve that stuff.
Ah, fuck it. I'll try once. Anyone know what the despawn time is on those items?