Best Guide For Terraria From A-Z

Hardmode ores

Hardmode Ores are generated upon destroying a Demon Altar or Crimson Altar with a Pwnhammer. They are immune to all types of explosions. You need at least a molten pickaxe to mine it.

A world only has the different 3 ores if their is Crimson or corruption in your world; EG- Palladium is in a corruption world but in a Crimson world cobalt will replace it.They're is no difference, both ores have the same stats.
Here are the ores in hardmode.

*Palladium Ore is an orange-colored Hardmode ore which can replace Cobalt in a given world. It appears similar to Copper Ore but appears slightly more saturated.

*Cobalt Ore is a blue colored ore which replaces palladium in a giving world.It is easy to identify because they're no other ores with color blue.

*Orichalcum Ore is a magenta-colored Hardmode Ore which can replace Mythril in a given world. Like all Hardmode Ores, Orichalcum is generated upon destruction of a Demon Altar with a Pwnhammer.

*Mythril ore is the replacement for orichalcum in a giving world.By destroying 2 demon alters will result in the ore generating in your world.

*Titanium Ore is a Hardmode ore which can possibly replace Adamantite in a given world. Titanium, like all Hardmode ores is generated upon destruction of a Demon Altar with a Pwnhammer or higher. Like Adamantite, a Mythril Drill/Orichalcum Drill (or their Pickaxe-equivalents) or better is required to mine it.Also the best ore out of the 3 in a world.

*Adamantite Ore is the highest tier of the three Ores available in Hardmode it replaces titanium. It spawns upon the destruction of every third Demon Altar or Crimson Altar. A Mythril/Orichalcum Drill or better is required in order to mine Adamantite on both the PC and console versions of the game, as of Version 1.2's release. It is used to craft the Adamantite Forge and Adamantite Bars. An Adamantite Forge, crafted from 30 Adamantite Ore and one Hellforge, is required in order to craft Adamantite Bars.

*Chlorophyte is a Hardmode ore found in the Underground Jungle. A pickaxe or drill with at least 200% pickaxe power is required to mine it (Drax or Pickaxe Axe and above). When Hardmode starts, Mud and Jungle Grass located in the Underground Jungle will begin to convert into Chlorophyte Ore. Once seeded, it will spread to adjacent Mud and Jungle Grass blocks.It's also the best ore in the game.