Origin
Metamorphic rocks arise from the transformation of existing rock types
Process called metamorphism, which means "change in form".
The original rock is subjected to heat and pressure, causing profound physical and/or
chemical change
Formation zone (ratio of heat and pressure)
upper zone - epizone
middle zone - mezozone
lower zone – katazone
Types of metamorphism
Regional metamorphism -- affects a large area; commonly due to
mountain building; foliated rocks common
Contact metamorphism -- rocks near igneous intrusion get baked;
produces non-foliated met. Rocks
EPIZONE
P – decisive, thin 1-2mm slak texture, directional texture: clay shale,
phyllite, talk schist
MEZOZONE
P – T equaly decisive, thick >2mm slak texture, directional texture: schist
(mica)
KATAZONE
T – decisive, thin 1-2mm slak texture, directional texture: clay shale,
phyllite, talk schist
EPIZONE
Clayslate: composed clay minerals and quartz grains and the typical
color is gray. Water resistrant.
Phyllite: foliated metamorphic rock created from slate that is further
metamorphosed so that very fine grained white mica achieves a
preferred orientation . Typicaly black, dark gray, thin slated (mm),
shiny
EPIZONE
Greenschist: green minerals such as chlorite, serpentine and platy
minerals such as muscovite and platy serpentine, thin slated (mm),
EPIZONE
Talc schist: soft, talc mineral. Light coloured
Serpentinite:
- green – black
-Serpentine mineral, quartz, calcite, pyrite
-can be polished
-strong
MEZOZONE
Schist (mica)
- sparkles (mica content), grey
- biotite, muscovite, feldspar, quartz
- local building material
KATAZONE
Gneis:
- looks like granite, BUT:
- directional terxture
- minerals: quartz, feldspar, plagioclase, biotite, amphibole
Crystaline texture, measonary stone, load bearing structure, ornamental
stone, crashed stone (ballast under rails, roads, concrete agregate)
KATAZONE
Marble
Crystaline texture, any colour (bright), Fizzles to acids
Calcite veins, fells colder than limestone (becouse wery dense)
Load bearing structure, Ornamental stone, chemistry