Lab 4: Metamorphic Rocks Flashcards
Andalusite
cruciform habit (look for a cross)
hardness = 6.5 -7.5
Garnet
occurs in well formed 12 sided crystals**
conchoidal fracture**
hardness of garnet
7-7.5
Kyanite
blue colour**
hardness = 5 parallel to long direction of crystal + 7 across crystal**
blade shaped crystals**
Serpentine
(its opaque green but do not say green)
(also asbestos)
greasy texture**
massive or fibrous**
hardness of serpentine
3-5
Staurolite
prismatic habit**
cross shaped crystal habit**
hardness of staurolite
7-7.5
Talc
greasy feel**
white, gray, light green
hardness = 1 **
Gneiss foliation
foliated
banding
gneiss protolith
shale (or felsic igneous rock)
gneiss metamorphic grade
high
minerals found in gneiss
same minerals as granite and diorite
garnet, staurolite, kyanite, sillimanite
what mineral is NEVER is gneiss
muscovite
Marble foliation, properties, minerals
non-foliated
reacts with acid
scratched by nail
contains calcite
marble protolith
limestone or dolostone
marble metamorphic grade
low to high
Phyllite
foliated
irregular (wavy) cleavage
silky/satiny lustre
phyllite protolith
shale
phyllite metamorphic grade
low
phyllite minerals
chlorite
Quartzite foliation, properties, minerology
non-foliated
not scratched by nail
does not react with acid
contains quartz
quartzite protolith
quartz sandstone
quartzite metamorphic grade
medium to high
Schist foliation
foliated - schistosity + porphyroblasts
schist protolith
shale
schist metamorphic grade
low to medium (medium once porphyroblasts appear)
schist minerals
biotite + porphyroblasts:
garnet, staurolite, andalusite, kyanite
if no porphyroblasts, it is a biotite schist
Slate
regular cleavage
foliated
non-lusterous
slate protolith
shale
slate metamorphic grade
very low
slate minerals
muscovite or chlorite
what do andalusite, sillimanite and kyanite have in common
polymorphs
metamorphic process of shale
slate, phyllite, schist, gneiss
how do you determine the metamorphic grade of quartzite and marble
fine grained = low metamorphic grade
coarse grained = high metamorphic grade
(the temp and pressure are like water and make the crystals grow)
contact metamorphism
normally near a volcano causing high temperature and shallow (=low pressure)
burial metamorphism
low temp and low pressure. Rocks are just underground which results in pressure and higher temp then the surace
which kinds of metamorphism resulte in non-foliated rocks
burial and contact
regional metamorphism
rocks are buried deep in the crust. associated with convergent plate boundaries and formation of mountain ranges
high temp, high pressure
subduction zone metamorphism
takes place at very high pressures and low temperatures at subduction zones
high pressure, low temp
hydrothermal metamorphism
occurs at mid ocean ridges. Cold water is drawn into the crust and heated as it passes through. Then it is released onto the seaflood near the ridge. This changes the original olivine and pryoxene minerals in the rock to chlorite and serpentine
which rocks are shit for estimating metamorphic grade
calcite, quartz, feldspars,
order from lowest grade to highest grade of metamorphic index minerals
chlorite, muscovite, biotite, garnet, staurolite, kyanite, Sillimanite
Contact metamorphism results in what kind of rocks
Non-foliated rocks
Burial metamorphism results in what kind of rock
Non foliated
Regional metamorphism results in what kind of rock
Slates, phyllites, Schists, gneiss
Subduction zone metamorphism creates what rocks
(High pressure, low temp)
Foliated rocks
