Geology & Rocks
Phyllite
Phyllite is a metamorphosed clay slate in grey, grey-green or silvery tones. The rock gives good soil when it weathers — rich in lime and other minerals.
Phyllite. Photo: James St. John, CC BY 2.0, via Wikimedia Commons.
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Phyllite is metamorphosed clay slate. It occurs in the colours grey, grey-green and silvery depending on how much carbon or iron it contains. It can have a glossy appearance because of the pressure it has been subjected to.
The rock gives good soil when it weathers, because it is rich in lime and other minerals — which is why much of Norway’s best agricultural land lies on phyllite ground (particularly in parts of Trøndelag and Gudbrandsdalen).
Rock type
Altered (metamorphic). Phyllite forms when clay slate is subjected to raised pressure and temperature, which recrystallises the minerals into a flat, parallel structure that gives it the characteristic sheen.
Photo: James St. John, CC BY 2.0, via Wikimedia Commons.