How long do dropped items persist?

Question

How long do dropped items persist in Terraria? I somehow dropped a gold pick in a corner I couldn't get to, and when I went to retrieve it, it had disappeared. Under what conditions do dropped treasure disappear?

Answer 1

It seems that there is a limit of 200 "loose" items at once, and if that limit is exceeded then the oldest item disappears. Also, quitting the game destroys all items on the ground.

http://wiki.terrariaonline.com/Items#Despawning

Answer 2

There is no time limit, you can keep an item on the ground for as long as you want just as long as you don't turn off the server or exit the single player world. There is however a 200 item limit that can be on the ground. As it states on the wiki it was never confirmed but was proven by using the chest duplication glitch(patched). This is to prevent the world from being overwhelmed with unneeded cleaning and item lag(too many non-active tiles(items) on the floor can cause server/single player lag). @Joseph Kendall also states this but he put it into a more simplistic and easy-to-read answer(for the lazy). Coins count as 1 item even if it is in multiple. For Example: When you pick up a bronze coin it might say 93 but on the Terraria code it will count as one item on the floor. In the condition of your gold coin, I'm sorry, I know the pain of losing gold coins(believe me i lost platinum before(100 gold coins coin tier)) but you probably logged out of your world and it disappeared, if not then you might have picked it up without noticing.