common to rocks affected by regional metamorphic compression typical of orogenic belts....

FOLIATION Lemuel Libres

Lopez, Sta. Mae

Banjal, Sajed

FOLIATION

common to rocks affected by regional metamorphic compression typical of

orogenic belts.

characteristic of metamorphosed rocks in which minerals are aligned in one direction so that the rock can readily be split into thin layer

any penetrative planar fabric present in rocks.

PRESENTATION NAMECompany Name

Slate-F

Migmatite-F

Gniess-F

Schists-F

Quartzite-NF

marble (CaCO3)

Marble-NF

Phyllite-F

Marble-NF

Appearance Under Microscope

Non-foliated Foliated

Development of Foliation

Types of Foliation

“Slaty”......is composed of platy minerals that are too small to see

“Phyllitic “ ....is composed of platy minerals that are slightly larger than those found in slaty cleavage,

“Schistose”......is composed of larger minerals which are visible to the unaided eye

“Gneissic”....is composed of alternating bands of dark and light minerals.

foliated metamorphic rock: slate

foliated metamorphic rock: Phyllite (higher T, P than slate)

foliated metamorphic rock:Schists (higher T, P than phyllite)

…new minerals grow -- garnet (large, roundish grains)

foliated metamorphic rock: Gneiss (higher T, P than schist)

banding of quartz/feldspar and ferromagnesian minerals