ore
砿 centers on unrefined mineral material: ore, the rocky substance mined from the earth before it is processed into metal.
砿 is a modern Japanese character formed from 石 (stone) and 広 (wide), likely created to represent ore as a wide-spread stone resource. The exact historical development is uncertain.
Stone 石 on the left and wide 広 on the right: imagine a wide expanse of stone that contains valuable ore waiting to be mined.
For コウ, picture a miner striking ore with a pickaxe and hearing a loud 'koh!' sound: koh -> コウ, as the stone reveals its hidden treasure.