Over the women's pool was a clear glass skylight, through which scattered sunlight would shine down onto an 80-kilogram rock, which is a prized possession of Peitou Hot Springs Museum- "Peitou Stone" Peitou Stone-hokutolite-is the only mineral in the world to be named after a place in Taiwan, and is only found in Peitou and the hot springs of Tamagawa in Japan.
就在婦人浴池中心，透過二樓玻璃天窗灑下幾道朦朧的光線，投射在一顆八百公斤的大石上，那是北投溫泉博物館的鎮館之寶──「北投石」。北投石是全世界唯一以台灣地名命名的礦石，是一種只出產在台灣北投與日本玉川溫泉的稀有礦石。