Originally Posted by Maza
I finally got the casing open of my Pokemon Gold cartridge and managed to change that battery. Trust me, it is very very simple if you read through that guide even once. Although I accidentally dropped some tin on the chip but since the game works just fine, it couldn't have hit any critical spot :). So just to warn all of you not-so-experienced-ones when you are wielding that soldering iron, keep it in the upwards position while holding it (to prevent any of the tin leavings from dropping in the wrong places). Pretty common sense but I just wanted to point that out :).
If i remember correctly it is a mix of tin and lead