Metamorphic rocks

Metamorphic rocks

Marble

Protolith: Limestone or dolostone Composition: Calcite (or dolomite) Grade: Low to medium Metamorphism: Usually contact, but can be regional

Quartzite

Protolith: Quartz sandstone Composition: Quartz Grade: Any grade (usually medium to high) Metamorphism: Contact or regional

Gneiss

Protolith: Granite or schist Composition: Quartz, feldspar, biotite, hornblende Grade: High Metamorphism: Regional

Phyllite

Protolith: Shale -> slate Composition: Mica (muscovite, biotite), chlorite, quartz Grade: Low to medium Metamorphism: Regional

Garnet schist

Protolith: Mudstone or shale Composition: Garnet, mica (muscovite, biotite), quartz Grade: Medium to high Metamorphism: Regional

Mica schist

Protolith: Shale or mudstone Composition: Muscovite, biotite, quartz, feldspar Grade: Medium Metamorphism: Regional

Talc schist (soapstone)

Protolith: Ultramafic rocks (like peridotite) Composition: Talc, chlorite, maybe amphibole Grade: Low Metamorphism: Typically regional, sometimes contact

Slate

Protolith: Shale or mudstone Composition: Mica (very fine), quartz, chlorite Grade: Low Metamorphism: Regional