塚原温泉 火口乃泉
Tsukahara Onsen Kakou-no-IzumiOperated by · 別府白土鑛業株式会社
硫
Sulfate
+ 含鉄(II,III)泉 · アルミニウム泉
- Color
- faintly yellow, clear
- Taste
- moderately sour, weakly astringent, moderately metallic
- Odor
- nearly odorless
Aluminum-Hydrogen Sulfate spring
pH 2.0AcidicHot source · 50°CIron-richHigh silicaUltra-acidic
Composition fingerprint3.3 g/kg dissolved · Hypotonic
Al³⁺54
H⁺20
SO₄²⁻86
HSO414
◀ CationsAnions ▶
- Aluminum Al³⁺
- shows up in acidic volcanic water.
- Sulfate SO₄²⁻
- "gypsum / Glauber's salt" — vessels and wound healing.
Known good for
- Aches & jointsstiff shoulders
- Skin conditionsatopic skin, eczema
- Circulationtired legs
- Sensitive-skin cautionbroken or dry skin
A strongly acidic sulfate spring (pH 1.9-2.0) loaded with iron and aluminum — a rare chemistry profile in Japan. The water emerges at over 50 °C carrying a faint yellow tint, oxidizing reddish-brown on contact with air, with sharp prickling acidity and a clear metallic-astringent taste. Metasilicic acid at a generous 292 mg/kg adds a thin silica film on top of the iron-rich body. The 'kakou-no-izumi' (crater spring) has a long track record for stubborn skin conditions.
Sampled at mixing tank·Analyzed Nov 21, 2024·公益社団法人 大分県薬剤師会検査センター·Cert no. 大薬検 第7R-24110011号
