METAMORPHIC ROCKS TEXTURES

METAMORPHIC ROCKS

Metamorphic rocks form when intense heat, intense pressure, and/or the action of hot fluids deform, or change, previously existing rocks. The rocks can recrystallize, break, and flow.
Metamorphism can occur by contact with hot magma bodies (contact metamorphism) or by action of differential stress (regional metamorphism).

Common Metamorphic Rocks Textures

most images contain a cm-scale for clarity

1

CONTACT METAMORPHISM
Equigranular crystalline texture
(macrocrystalline)
marble

2

CONTACT METAMORPHISM
Equigranular crystalline texture
(microcrystalline)
quartzite

3

REGIONAL METAMORPHISM
Crystalline foliated texture
(Foliation: flat, scaly crystals lay parallel to one another)
schist

4

REGIONAL METAMORPHISM
Crystalline foliated texture
(Foliation: flat, scaly crystals lay parallel to one another)
schist

5

REGIONAL METAMORPHISM
Newly formed, flat crystals separate in different bands
with different composition (silicic and mafic)
gneiss

6

REGIONAL METAMORPHISM
Increasing temperatures cause melting of the
silicic components, that recrystallize as igneous minerals
migmatite

All pictures © Alessandro Grippo

All pictures: samples from the Santa Monica College collection, Santa Monica, California

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