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Yunohana

Yunohana1

Yunohana (湯の花) are the deposits and precipitates of insoluble components found in many hot springs. Terms such as Yuka (湯花), Yunohana (湯の華), as well as Yuka (湯華) also refer to these sediments, which differ from dirt. In scientific literature, such deposits are described as sinters, particularly outside of Japan.

As hot waters gush out of underground springs at high temperatures then come in contact with the surrounding air, the subsequent drop in temperature decreases a fluid's mineral solubility. As a result, some dissolved minerals in the water congeal. Moreover, these mineral waters interact with the air, causing further precipitation. Various bacteria also interact with mineral solvents in complex ways when forming sinters. These newly formed solids can develop shapes akin to flower petals, hence in Japanese are known as"yunohana," which literally means "hotspring flowers." Precipitating sediments often appear in thread-like forms that adhere to bathtub walls or to hot water outlets. Some onsen facilities post notices that these should not be mistaken for dirt. Moreover, at some Japanese hot resorts, such mineral deposits are collected in wooden tubs known as yubatake (湯畑), then scooped up and later sold as bath salts.

Components

The actual chemical composition of yunohana varies considerably depending on location. For example, at Beppu Onsen and Okushiobara they appear on clay-covered surfaces near volcanic fumes adhering to rocks. At Onnetō Hot Falls in Hokkaido the manganese-rich waters produce dark grey deposits. Moreover, at the Arayu spa in Tochigi Prefecture they resemble tiny jade pebbles. In some acidic waters such as those of Kusatsu Onsen, they appear as sulphurous flowers. However, at Beppu Onsen's sulphur- and silica-rich waters, they manifest in different shapes. Yunohana have been observed in multiple forms and are typically rich in sulphur, calcium, aluminium, iron and silicon.

Uses

Since these mineral condensates are often rich in sulfur, occasionally they are used as insect repellents. Yunohana was also sometimes burned under beehives when collecting honey and bee larvae. Moreover, yunohana was formerly used to plug mole holes and to repel and poisonous insects.

Yunohana have also been used to create gunpowder as well as in the production of insulators for utility poles . Moreover, they have been used to polish glass, as well as to bleach gourds. They are sometimes used as folk remedies and to adjust the taste of pickles

Most commonly today, yunohana is packaged and sold as bath additives. However, when used as bath additives, the sulfur-rich ingredients can sometimes damage bath tubs [reference needed]. On the other hand, syunohana consisting mainly of calcium carbonate, sodium sulfate, and calcium sulfate are less corrosive. Therefore, consumers should check yunohana ingredients before adding it to a tub.

Handling Precautions

Some prefectural fire prevention ordinances regulate the storage and transportation of yunohana with a high sulfur content that are highly flammable in amounts exceeding 20 kg. [reference needed] In order to avoid unintended combustion, some spas such as Nasu-Yumoto Onsen in Tochigi Prefecture package their sulfur-rich hot-spring products in pre-moistened dumpling-shaped packages [reference needed]. In addition, Japan's national Fire Defense Law places places restrictions upon the storage and transportation of yunohana with high sulphur levels in amounts exceeding 100 kg. [reference needed]

See also

• Calcareous_sinter