Rock Group

Metamorphic

Grain Size

Chlorite forms a fine grain schistose matrix around larger garnet grains.

Composition

Chlorite-schist is made of aligned platy grains, called “schistosity”. This alignment can also make a chlorite-rich rock feel greasy. The texture of having coarse grains in a finer grained matrix is called porphyroblastic, i.e. the garnet grains are porphyroblasts.

Key Features

This rock was metamorphosed at greenschist conditions of around 500°C. The metamorphic garnet porphyroblasts that grew during the metamorphism form large brown/red coloured rhombic dodecahedron (12-sided structure with diamond shaped faces) minerals.