Tin Ore

This is the copper slot in worlds that rolled the alternate ore set, and the gear it makes is barely ahead of what you can build out of wood or cactus on your first night. Mine it when it is directly in your path, not as a goal. The armor you actually wear into your first boss will be made of something further down the chain, and getting there faster matters more than a marginal upgrade you wear for twenty minutes.

Bars are cheap stock for crafting stations, furniture and building, and slimes cough up enough ore that you accumulate it without ever going looking. Keep a stack for that and stop worrying about it.

A world running on tin still hands new characters copper tools, so the first pickaxe you hold does not match what is actually in the ground. Do not read your starting gear as a hint about which ore set you got. Go look at a cave wall instead.