Metamorphic rocks - Phyllite

Page / - last modified by Roelof Zwaan on 2021/09/30 15:18

Phyllite

last modified by Roelof Zwaan

on 2021/09/30 15:18

Table of Contents

Phyllite is a foliated metamorphic rock made up from flake-shaped mineral grains. This rock originates from shale and transformed from shale into slate, then in phyllite. If the rock is transformed any further it becomes first a schist and then a gneiss.

Characteristics

Due to the flake-shaped mica's present this rock breaks easily into sheets or slabs. This rock type can be distinguished from slate by its reflective sheen. Phyllite originate from regional metamorphism at convergent plate boundaries involving continental lithosphere, which mean it forms under low pressure and low temperature conditions.

Composition

Phyllite contains tiny grains of mica minerals and all the minerals present are smaller than what can be seen with the naked eye. However sometimes there are other metamorphic minerals present as crystals and these can be seen by the unaided eye. These crystals are called porphyroblasts. Its reflective color owes it to the fact that organic material present in the parent rock is transformed into graphite.

References

NEN-EN-ISO 14688-1:2019

https://geology.com/

Phyllite

Type	Metamorphic rock
Texture	Flaky
Clasts	Can be present
Hardness	Hard
Color	Grey, black or greenish
Minerals	Quartz or feldspar and tiny mica minerals
Touch	Smooth
Image	Phyllite

Contents

Characteristics

Composition

References

Phyllite