Wooden Scanner
Basic tier. Only shows one occurrence, even though there might be multiple ore veins in the chunk. Requires some XP!
Iron Scanner
First tier. Shows every vein, still needs XP!
Golden Scanner
Second tier. Shows every vein & needs no XP!
Iron Cage
Did I mention that the scanners may or may not explode when you try to pick them up? The iron cage nerfs this by 50% (stackable).