What is a Ferruginous Spring?
A ferruginous spring contains iron (II) and iron (III) ions totaling 20 mg per kilogram of spring water. Clear when it gushes from the source, it turns reddish-brown to golden when oxidized by air.
It has a distinctive metallic, rust-like aroma and a slightly bitter, astringent taste. The reddish-brown staining visible on the bathtub rim is an unmistakable visual signature.
Indications for Drinking
- Iron-deficiency anemiaDrinking this spring water may help address this condition by supplying easily absorbed divalent iron (Fe2+) directly to the digestive tract. This iron serves as a material for hemoglobin synthesis, supplementing dietary intake. For better absorption, consider taking it with vitamin C and avoid tea or coffee, whose tannins can interfere with the process.
How to Bathe in a Ferruginous Spring
- Fresh spring water is ideal — once heavily oxidized, the iron is less bioavailable.Ferruginous springs are richest in absorbable iron(II) ions right at the source. As the water is exposed to air, it oxidizes, turning reddish-brown and converting the iron into a less bioavailable form, diminishing its therapeutic effects when ingested.
- Avoid white towels and light-colored swimwear; iron staining is difficult to remove.The same oxidized iron compounds that color the water will also deposit on fabrics, creating rust-colored stains. These mineral stains are very difficult to remove from light-colored towels and swimwear, so it's best to use dark-colored items.
- A quick rinse with fresh water after bathing reduces the metallic smell (slightly reduces skin benefits).The distinct metallic smell of an iron spring comes from the mineral deposits left on your skin. While rinsing with fresh water removes this scent, it also washes away the gentle film of iron that helps retain body heat and promote circulation after your bath.
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References
Famous Onsen Areas with Ferruginous Spring
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