Why can't I mine Iron Ore in Minecraft? [duplicate]

Minecraft doesn't have a "tutorial", exactly, so it is difficult to understand the rules, the first time you play. If you visit the wiki however, you can find out a lot about the game.

In this instance, you'll find that in order to mine Iron Ore, you need a Stone Pick. A Wooden one will not work.

There are certain tiers of pickaxes (wooden, stone, iron, ...). If the iron ore breaks without dropping something, you are probably using a wooden pickaxe. A wooden pickaxe only works on stone and coal blocks. Try to use a stone pickaxe (same way to construct it, but with cobblestone instead of planks. You will see the iron ore will drop and you can pick it up.

Someone else has also asked this question and you can find it here: Why is my iron ore disappearing when mined with a wooden pickaxe?.

From what they said from the question, the simplest advice I can give you is that you need a stone pickaxe or greater to mine iron ore.