Fen

A minerotrophic mire — a peatland fed by groundwater or surface water rather than rainfall alone. German: Niedermoor (“low moor,” referring to its position low in the landscape relative to a raised bog’s dome).

Characteristics

• pH 4.5–7.0 — much less acidic than a raised bog
• Nutrient- and mineral-richer — groundwater carries dissolved minerals into the system
• Vegetation — dominated by sedges (Carex), reeds, and grasses rather than sphagnum moss
• Peat chemistry — lower humic acid concentration relative to raised-bog peat, but higher trace mineral content (notably iron)

Role in Balneological Tradition

Fen peat (Niedermoortorf) is the traditional source material for much of Central European Moortherapie — German and Austrian peat baths historically drew on fen deposits valued for their mineral content as much as their organic bioactives. This is a different chemical profile from the sphagnum-derived raised-bog peat that dominates Baltic/Nordic cosmetic peat, and helps explain why German Heilmoor products and Estonian/Finnish cosmetic peat products emphasize different active-compound stories.