塚原温泉 火口乃泉
Tsukahara Onsen Kakou-no-IzumiOperated by · 別府白土鑛業株式会社
Sampled at mixing tank
硫
Sulfate
+ 含鉄(II,III)泉 · アルミニウム泉
Classification
Aluminum-Hydrogen Sulfate spring
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.
pH
2.00
Acidic
Source temperature
50.3°C
Hot
Tonicity
3.31g/kg
Hypotonic
Free CO₂
2.20mg/kg
Low
- Color
- faintly yellow, clear
- Taste
- moderately sour, weakly astringent, moderately metallic
- Odor
- nearly odorless
Highlights
- Iron-rich
- High silica
- Ultra-acidic
- Top-decile hot
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