Metamorphic Rocks

Metamorphic means “change of form” in Greek.

Metamorphic rocks were all once other kinds of rocks. They were CHANGED to become metamorphic rocks.

Metamorphic rocks are made by heat and pressure.

When rocks are close to the mantle (by the hot magma) they are changed.

When rocks are pushed down below other rocks (plate movement) then the pressure also changes rock into metamorphic.

Metamorphic rocks are also made when plate are pushed together. The pressure from two huge tectonic plates can change rocks into metamorphic.

Shale turns to Slate

Schist turns to Gneiss

Minerals in Metamorphic Rocks

Rocks are made of minerals. Minerals in metamorphic rocks become tightly packed and large. (can CHANGE minerals into different minerals)

Minerals only found in metamorphic rocks: Chlorite

Garnet

Staurolite

kyanite

Identifying Metamorphic Rocks

Rock Color Foliated Grain Size

Slate Dark gray Yes fine

Schist Mixture No Medium

Gneiss Pink/gray Yes coarse

Marble Light No Coarse

Quartzite Light Not coarse

Using Metamorphic Rocks

Metamorphic rocks are used for many different things.

Marble is commonly used for buildings and sculptures.

Slate is used to make tiles for roofs.