Metamorphism &
Metamorphic Rocks
How do Metamorphic rocks form?
The rock that forms depends on:
Why Should You Study Metamorphic Rocks?
What are the 3 Agents of Metamorphism?
Heat ___________ the rate of chemical reactions.
Sources of Heat:
How does TIME affect transformations?
Lithostatic

Differential __________:
Chemically Active Fluids
Sources of fluids:
1) .
2) .
3) .
Types of Metamorphism
Regional Metamorphism
Contact Metamorphism
Alteration occurs because:
Aureole 
Width determined by:
Index
Minerals
Dynamic / Cataclastic Metamorphism
Mylonites 
How Are Metamorphic Rocks Classified?
Two Groups
foliation 
Foliated Meta. Rocks
Rock
Name
Slate
Phyllite
Schist
Gneiss
Typical
Minerals
Meta.
Grade
clays, micas,
chlorite
quartz, micas,
chlorite
low
micas, chlorite,
talc, garnet
hbl
qtz, feldspar,
hbl, micas
med-high
low-med
high
Features
of Rock
fine-grained,
splits uniformly
fine-gr, glossy
“crinkled”
Parent
Rock
shale,
vol. ash
shale
distinct foliation shale,
visible
carbonates,
basalt/gabbro
light & dark
shale,
bands
sandstone,
basalt/gabbro
felsic ign.
Amphibolite hbl
med-high dark, weak fol.
basalt/gabbro
Migmatite qtz, feldspar,
hbl, mica
very
high
felsic ign. &
sed. mixed
granite streaks
in gneiss
SLATE
(very fine-grained, foliated)
• formed by ____________, ___________ metamorphism
•
• used for
PHYLLITE
(fine-grained, foliated)
• glossy sheen
• coarser-gr. than slate
• “crinkled” appearance
SCHIST
(medium-grained, foliated)
• platy/elongate minerals
• _________________________ metamorphism
Schistose foliation 
GNEISS
(medium-grained, foliated)
• ______________
• ________________________ metamorphism
• Light bands  granular minerals. (______________________)
• Dark bands  platy/elongate min. (______________________)
AMPHIBOLITE  (med-gr, foliated) hornblende & plagioclase
(___________________ regional meta.)
Georgian Bay, Ontario, Canada
MIGMATITES (mixed rocks)
• _________________________ metamorphism
• High-grade meta. rx intermix w/ streaks of granite.
Nonfoliated Metamorphic Rocks
Nonfoliated Meta. Rocks
Rock
Name
Marble
Quartzite
Greenstone
Hornfels
Anthracite
Typical
Minerals
calcite,
dolomite
quartz
chlorite, epidote,
hornblende
micas, garnet,
quartz
carbon
Meta.
Grade
low-high
med-high
low-high
low-med
high
Features
of Rock
interlocking
grains
interlocking
grains, hard
fine-grained
green color
fine-grained,
hard, dense
black, lustrous,
subconchoidal
fracture
Parent
Rock
limestone,
dolostone
quartz
sandstone
mafic ign.
mudrocks
coal
Marble
C
• ________________________________ metamorphism
• Parent Rock =
How is Marble used?
metamorphism
QUARTZITE
• _____________________________________ metamorphism
• Parent Rock = ________________________
• Hard & compact w/ uniform strength
[breaks across grains rather than around them]
• used in __________________________________________
metamorphism
Greenstone  (____________________ meta)
• Parent rock = ________________________
(green color from chlorite, epidote, & hornblende)
Hornfels  (__________________________ meta)
• Parent rock = __________________________
• equidimensional grains
Anthracite 
• Parent rock = ___________________________
What Are Metamorphic Zones?
Isograd 
Does Metamorphism Relate to Plate Tectonics?
Low-temp/high-press  _______ part of subducting plate
High-temp./high-press  _______ part of subducting plate
High-temp/low-press  _________ meta. follows
Minerals used:
talc 
graphite 
garnet
kyanite 
asbestos 
Natural Resources
Chrysotile
{Chrysotile  silky fibers
95% of all asbestos used in the U.S.}
{Crocidolite  long, straight fibers
This variety presents a health risk.
EPA policies treat all asbestos the same.}
Ore Deposits
(hydrothermal contact meta.)
Ore
Copper
Iron
Mineral
Formula
Bornite
Cu5FeS4
Hematite
Fe2O3
Magnetite
Fe3O4
Lead
Galena
PbS
Tin
Cassiterite
SnO2
Tungsten Scheelite
CaWO4
Wolframite (Fe,Mn)WO4
Zinc
Sphalerite
(Zn,Fe)S
Uses
transportation,
communications
steel manufacturing
batteries, pipes, solder
plating, solder, alloys
metal hardening,
carbide manufacturing
batteries, brass making,
galvanizing iron