垂玉温泉 (山口旅館 元湯)
Tarutama Onsen (Yamaguchi Ryokan Motoyu)Operated by · 垂玉温泉 瀧日和
湯
Simple
- Color
- faintly yellow-brown and clear
- Taste
- faintly metallic
- Odor
- hydrogen sulfide
Calcium-Magnesium-Sodium Bicarbonate-Sulfate spring
Hot source · 45°CHigh silica
Composition fingerprint0.7 g/kg dissolved · Hypotonic
Ca²⁺35
Mg²⁺30
Na⁺21
HCO₃⁻55
SO₄²⁻41
◀ CationsAnions ▶
- Calcium Ca²⁺
- settling and calming; can leave a white mineral bloom.
- Bicarbonate HCO₃⁻
- "soda" — softens skin, leaves it smooth.
Known good for
- Aches & jointsstiff shoulders
- Smooth skindry, rough skin
- Recoveryfatigue, stress
A naturally flowing source feeding the Yamaguchi Ryokan motoyu at Tarutama Onsen in the southern Aso highlands. Classed as a simple thermal spring, weakly acidic and hypotonic with dissolved solids of 717 mg/kg, it nonetheless emerges hot at 45.3 °C. A standout 303 mg/kg of metasilicic acid puts it squarely in Japan's beauty-water family, leaving a fine silica film that makes skin feel noticeably smoother. The water comes up faintly yellow-brown and clear, carrying the distinct rotten-egg note of H2S and a light metallic edge — a simple spring with real character.
Analyzed Mar 24, 2021·株式会社三計テクノス
