MINERALS

Strontium ion: Main Effects & Top 5

Published May 5, 2026·1min read

Strontium ion (Sr²⁺) is a rare trace element with calcium-like properties. Its gentle astringent action tightens the skin.

Table of Contents

What is Strontium ion?
Main Effects
Strontium ion Top 5 Hot Springs

What is Strontium ion?

Strontium ion (Sr²⁺) is a rare trace element with calcium-like properties. Its gentle astringent action tightens the skin.

Main Effects

Calcium-like gentle astringent actionStrontium ions (Sr²⁺) bind with keratin proteins on the skin's surface. This process creates a mild astringent effect, which may help to gently firm and tighten the skin.
Extremely rare in JapanFor an onsen to be noted for its strontium content, it must contain at least 10 mg/kg of strontium ions. This standard is defined in the Ministry of the Environment's Mineral Spring Analysis Method Guidelines, and very few hot springs in Japan meet this threshold.
Often coexists with calcium ionsDue to their similar chemical properties, strontium is frequently found alongside calcium. It tends to appear in trace amounts in onsen waters that originate from seawater or have passed through limestone layers.

Strontium ion Top 5 Hot Springs

Top 5 hot springs registered on this site with the highest content.

RANKING BY THIS MINERAL CONTENT

References

MINERALMay 5, 2026· 1min read

Calcium ion: Main Effects & Top 5

Calcium ion (Ca²⁺) exerts an astringent action that tightens the skin. Its calming properties help soothe flushing and inflammation after bathing.

MINERALMay 5, 2026· 1min read

Manganese ion: Main Effects & Top 5

Hot springs containing manganese ion (Mn²⁺) at ≥ 10 mg/kg are rare in Japan. This trace element keeps the stratum corneum supple and supports the skin's antioxidant defense.

MINERALMay 5, 2026· 2min read

Metasilicic Acid: The "Beauty Spring" Standard Mineral & Top 5 Onsen

Metasilicic acid (H₂SiO₃) is a natural moisturizer also found in skincare lotions. Hot springs containing more than 50mg/kg are called "beauty springs" — leaving skin hydrated long after bathing. This is one of the therapeutic spring criteria in Japan's Mineral Spring Analysis Guideline (Table 1-1).