METAMORPHISM
AM o
TRANSPORTATION
CKYSTALLIZATION
Th« rock cycle
CRITERIA USED TO CLASSIFY
METAMORPHIC ROCKS:
1. TEXTURE--THE SIZE, SHAPE, AND
RELATIONSHIP OF THE MINERAL
GRAINS TO EACH OTHER
2. COMPOSITION-WHAT MINERAL OR
MINERALS ARE PRESENT
OBJECTIVES IN STUDYING
METAMQRPHIC ROCKS
1. IDENTIFICATION AND CLASSIFICATION OF
THE ROCK
2. IDENTIFICATION OF THE ORIGINAL ROCK
3. TELL WHAT TYPE OF METAMORPHISM
OCCURRED
4. TELL THE GRADE OF METAMORPHISM
AGENTS OF METAMORPHISM
1. HEAT
A. NEARBY MAGMA
B. RADIOACTIVE DECAY
C. NORMAL GEOTHERMAL GRADIENT
D. FRICTIONAL HEAT DURING
DIASTROPHISM
2. PRESSURE
A. OVERBURDEN PRESSURE
B. TECTONIC PRESSURE
C. HYDRAULIC PRESSURE
3. CHEMICALLY ACTIVE FLUIDS
A. JUVENILE WATER
B. METEORIC WATER
C. CONNATE WATER
D. WATER OF FORMATION
TYPES OF CHANGES DURING METAMORPHISM
1. SHEARING
2. GROWTH OF NEW MINERALS
A. HIGH TEMP./HIGH PRESSURE
POLYMORPHS
B. NEW ELEMENTS INTRODUCED
3. RECRYSTALLIZATION
4. BAKING
5. DIFFERENTIAL MELTING
6. SEGREGATION OF MINERALS
7. ORIENTATION OF MINERAL GRAINS
A. FOLIATION
B. LINEATION
C. BANDING
TABLE 6-1. CLASSIFICATION OF MS7AMOHPHIC ROCKS
ORIENTED GRAINS
TEXTURE
Foliated
Fclia'-ed
cr
Uneated
PARTICLE SIZS
COMPOSITION
COMMENTS
ROCK NAME
Fine grained,
minerals not
visible
Clay minerals, micas
Dense
Slate
Satiny luster
Phyllite
Medium to coa.-ss
grained, minerals
visible
Clay minerals, micas
..
Muscovite, biotite. chlorite, talc,
garnet, kyanite. s'aurolita,
quartz, ferromagnesian
minerals.
Feldspars, quart!, micas,
ferromagnesian minerals.
Banded
Rock name Is preceded by Schist
diagnostic minerals
such as garnet mica
schist, kyanite biotit?
schist, hornblende schist
Gneiss
Banding due to
alternation of light and
dark minerals
i
Hardness of 3: fizzes
rapidly with dilute HCI
Marble
Dolomite (Ca.Mg) (COj),
Fizzes with dilute HCI
only when powdered
Dolomitic
Marble
Quartz {SiOiJ
Hardness of 7; breaks
across grains
Quartzite
u
E
O
Amphiboles
Generally black; prismatic Amphibclite
crystals with 2 directions
c.' cteavage-at 120*
0
Anything that could be a
conglomerate
Breaks across grains as
well as around them
Metaconglomerate
Clay minerals, micas
Carbonaceous material
Dense, dark colored
Slack, shiny, conchoidal
fracture
Kornfels
Anthracite Coal
Medium to coarse
grained, minerals
visible
Calcite (CaCO,)
M
<
C
O
Q
IU
Fine grained,
minerals not
visible
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DIMENTARY ROCKS
IGNEOUS ROCKS
LOW GRADE
^^^^_
HI
CO
MEDIUM GRADE
HIGH GRADE
INDEX MINERALS
^
Original rock
Chlorite Zone
Biotite Zone
Garnet Zone
Staurolite zone
Sillimanite
zone
Rhyolite
Rhyolite
Biotite
schist or
gneiss
Biotite
schist or
gneiss
Biotite schist
or gneiss
Biotite schist
or gneiss
Granite
Granite
Granite
gneiss
Granite
gneiss
Granite
gneiss
Granite
gneiss
Basalt
Chloriteepidotealbite schist
Chloriteepidotealbite schist
Albiteepidote
amphibolite
Amphibolite
Amphibolite
Limestone and
dolostone
Limestone and
dolostone
Marble
Marble
Marble
Marble
Quartzite
Quartzite
Quartzite
Quartzite
Quartz-mica
garnet schist
or gneiss
Quartz sandstone Quartzite
Clayey
sandstone
Micaceous
sandstone
Quartz-mica
schist
Quartz-mica
garnet schist
or gneiss
Quartz-mica
garnet schist
or gneiss
Shale
SUte
Phyllite
Biotitegarnet phyllite
Biotite-garnet
Staurolite
schist
Products of metamorphism
Siliimanite
schist or
gneiss
METAMORPHIC ROCKS
Sample Grains: Visible or not?
number Oriented or non-oriented?
Type of orientation?
NAME
Grain size
Mineral composition
Hardness, HCI reaction,
luster, color, etc.
LAB SEC.
Rock name
Possible original
rock
METAMORPHIC ROCKS
Sample Grains: Visible or not?
number Oriented or non-oriented?
Type of orientation?
NAME
Grain size
Mineral composition
Hardness, HCI reaction,
luster, color, etc.
LAB SEC.
Rock name
Possible original
rock