Foliation (geology)
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Foliation in geology refers to repetitive layering in metamorphic rocks. Each layer can be as thin as a sheet of paper, or over a meter in thickness. The word comes from the Latin word folium, meaning
Gneiss, a foliated metamorphic rock.
Quartzite, a non-foliated metamorphic rock.
Porphyroblast
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A porphyroblast is a large mineral crystal in a metamorphic rock which has grown within the finer grained matrix. Porphyroblasts are commonly euhedral crystals, but can also be partly to completely ir
Thin section of a garnet porphyroblast (black) in a mica schist that contains foliated trails of small inclusions (white and grey)
An almandine-garnet growing as a porphyroblast in a quartzitic gneiss
Dark-coloured porphyroblasts of garnet in mica schist at Syros, Greece
Large almandine porphyroblasts growing in gray-green schist