Phyllite
“Between slate and schist”
Metamorphic
Phyllite is a fine-grained metamorphic rock that represents a stage of metamorphism between slate and schist. Its surface has a characteristic silky or satiny sheen caused by microscopic mica crystals that are just beginning to grow large enough to reflect light.
Composition
muscovite, chlorite, quartz, feldspar
Where Found
New England (USA), Wales (UK), Alps, Appalachian Mountains
Mohs Hardness
2.5-4
Fun Fact
Phyllite's name comes from the Greek 'phyllon,' meaning leaf, because it splits into thin sheets that resemble leaves.
Test Your Knowledge
In the progressive metamorphic sequence starting from mudstone, what rock type immediately follows phyllite?
Related Specimens
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