第 10 集: 地質學家探索廢棄錳礦，發現有毒的菱錳礦壓艙物

10

The geologists set out for a historical manganese mine, with Yoko hesitantly in the lead, after Nagi has to miss out due to a last-minute excursion. We learn some properties and uses of manganese. Blocked by a collapsed rail tunnel, the team searches for fallen samples along the tracks. They discover rhodonite and rhodochrosite in quantity, suggesting prohibited use of potentially toxic tailings as track ballast. Perhaps a long-ago rail crew used their cargo for emergency repairs, though the actual answer remains unknown. (Source: Wikipedia)