地蔵源泉（県有）
Jizo Spring (prefecture-owned)酸
Acidic
+ 含硫黄泉 · Sulfate · Chloride
- Color
- colorless and transparent
- Taste
- not recorded
- Odor
- hydrogen sulfide odor present
Hydrogen-Aluminum Sulfate-Chloride spring
pH 2.0AcidicHot source · 50°CUltra-acidicHigh silicaSulfur-rich
Composition fingerprint1.8 g/kg dissolved · Hypotonic
H⁺37
Al³⁺20
Ca²⁺14
SO₄²⁻55
Cl⁻34
◀ CationsAnions ▶
- Hydrogen H⁺
- makes the water acidic — sharp and bactericidal.
- Sulfate SO₄²⁻
- "gypsum / Glauber's salt" — vessels and wound healing.
Known good for
- Skin conditionsatopic skin, eczema
- Circulationtired legs
- Aches & jointsstiff shoulders
- Sensitive-skin cautionbroken or dry skin
The Jizo source at Kusatsu yields sharply acidic water: at pH 2.0 it stings slightly on contact, built on aluminium with sulfate and chloride behind it, and carrying enough hydrogen sulfide to be classed as a sulfur spring of the H₂S type. It runs colorless and clear, yet announces itself with an unmistakable rotten-egg note. Mineralization is moderate at roughly 1,750 mg/kg of dissolved solids, but metasilicic acid is generous at 234 mg/kg, leaving a thin silica film that softens the edge of the acidic bite.
Sampled at wellhead·Analyzed Aug 4, 2023·一般社団法人 群馬県薬剤師会（環境衛生試験センター）