Plinthite (derived from Greek πλιντος, stone) is a soil term for an iron-rich, humusarm mixture of clay, quartz and other materials.
It usually occurs as dark red spots in plate, polygon or netted structures. Due to repeated wet and dry conditions, especially by exposure to the heat of the sun, plinthite changes irreversibly in a hard layer of iron or irregularly shaped hard aggregates. In humid conditions, plinthite is usually quite sturdy, but it can still be pierced.
Plinthite is the result of far-reaching segregation of iron, often with additional enrichment of iron from other horizons and / or higher soils. The material is created under tropical conditions and is characteristic of the often very thick red tropical soils.
Many materials mentioned earlier in the past are now covered by the plinthite description.
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