mineral, ore
鉱 centers on raw mineral resources extracted from the earth: ores and minerals, especially those containing metal.
鉱 is the modern simplified form of 礦. The older form combines 石 (stone) with 廣 (broad), suggesting a broad deposit of stone or mineral. The modern form replaces 石 with 金 (metal) and simplifies 廣 to 広, emphasizing metallic ores.
The left side is 金 (metal) and the right side is 広 (broad). Picture a broad vein of metal ore running through rock: 鉱 is mineral ore.
For コウ, imagine a miner shouting 'Coal!' when they find a broad vein of ore: coal -> コウ, and the metal 金 is right there.
mine (ore)
mineral
coal mine; (coal) pit; colliery
ore; mineral; crystal
mining industry
gold ore; gold deposit
smelting furnace; blast furnace
vein (of ore); reef; streak; lode
iron ore
mining and manufacturing industry
mining
mineral spring
mineral deposit; ore deposit
mineral exploration
mine pollution
atacamite
algodonite
uranium ore
wurtzite
chromite