Iron

Iron is a metal resource from vanilla Minecraft, and an ingredient in nearly every recipe in IC² in one form or another.

Forms

These forms of iron are seen during ore processing:

•  Iron Ore
•  Crushed Iron Ore
•  Purified Crushed Iron Ore
•  Iron Dust
•  Tiny Pile of Iron Dust

These forms of iron are seen during metal shaping:

•  Iron Ingot
•  Block of Iron
•  Iron Plate
•  Dense Iron Plate
•  Iron Item Casing
•  Shaft (Iron)
•  HV Cable

Uses

Pretty much everything ever.

No, seriously. The first thing you'll need iron for is crafting the  Forge Hammer to make metal plates, in order to craft an  Iron Furnace or  Basic Machine Casing for your first  Generator - there are very few things that don't use iron in IC², and most of them are subcomponents of things that do! Or maybe they're steel instead, which is just an upgrade of iron anyway.

You're going to need lots of this stuff. We mean it.

Crafting

Basic crafting is the same for (almost) every metal. Any pre-ingot form, except for the  Tiny Pile of Iron Dust, can be smelted into an ingot.

Smelting anything but dust is a waste of resources, though - check the ore processing page to see how to maximize your output.

9 ingots craft into a block and vice versa.

Dust comes from 9 small piles, but you can't craft small piles out of a single dust like you can craft ingots out of a block.

For parts that you make using this metal, plates and item casings and so forth, there's a page for that already.