Materials

Materials which can be specifically identified by their properties, such as wood or iron. But is not limited to what tools can be made them, such as emerald or quartz.

Netherrack
Burns forever.

Obsidian
Is used for enchanting table, maybe conducts XP?

Wood
Can make crafting table.

Iron
Can be used to make iron golems, in combination with a carved pumpkin.

Gold
Golden tools are more easily enchanted than non-gold tools, maybe conducts XP better, less resistance? Can be combined with Redstone to make a Clock, so is related to time somehow?

Diamond
Is used to make enchanting tables, maybe allows XP from-player-to-table to happen?

Emerald
Witches' have an emerald on their hat and use their potions conditionally, so maybe has a conditional property?