Lodestone Chunks are an ore that can generate naturally in the world's Underground and Cavern layers upon defeating Coznix, The Fallen Beholder. The generating of the ore into the world can be done up to 3 times; defeating Coznix after that will generate Valadium Chunks until its third generation, and after that nothing. Additionally, defeating Coznix in Expert Mode will generate extra Lodestone Chunks compared to Normal Mode. It can also be found in Scarlet Crates in Hardmode after defeating Coznix.
By default, defeating Coznix, The Fallen Beholder has a 50% chance of generating Lodestone Chunks, with the other 50% chance generating Valadium Chunks instead. After either ore has been generated 3 times, the opposite ore becomes guaranteed to generate. As a result, Coznix must be defeated 6 times in total to generate all the possible Lodestone and Valadium Chunks possible for the world.