So when ores respawn, they seem to respawn as a random ore vein based on the level. Mine a gold vein, it respawns as an iron vein. The problem comes with players only mining only the good ore veins; stuff like copper, iron, even silver don't typically get mined ever. that leads to all the high demand ores like gold and mythril getting mined, and when they respawn not all of them respawn as the ore they were originally. players don't mine these ores, mine what mythril/gold had respawned till there is none left