1 The Myoban area is a geothermal place, and onsen steam comes into the Yunohana huts from under the floor.
2 The steam, while going up through straws and blue clay, cools down and turns into water. At the same time, the hydrogen sulfide in the steam, reacting to oxygen, turns into sulfuric acid.
3 When the water containing sulfuric acid reaches the layer of blue clay, it is combined with iron and aluminum in the blue clay and turns into sulfuric acid salt.
4 This sulfuric acid salt emerges onto the surface of the floor with the flow of the steam and gets crystalized like frost columns.
5 The crystalized salt, called ‘Yunohana’, grows for some weeks to one month. Then, it is reaped at the bottom by iron tool.
