Petrology Flashcards
Igneous & Metamorphic rocks and systems
Protolith
What is a
The original unmetamorphosed rock from which a given metamorphic rock has originated from
Is called a what
Foliation
What is
a planar fabric or layering in metamorphic rocks resulting from the alignment of mineral grains, compositional banding, or flattening of rock components under directed stress
Is called what
Igneous layering
What is
Repetitive, subparallel bands or sheets of varying mineralogy or texture in plutonic rocks as a result of magma differentiation
Is called what
Greenstone
What is
Fine-grained granoblastic rock of low-grade regional metamorphism and mafic composition; chiefly contains chlorite, epidote, and actinolite; also greenschist if schistose
Is called what
Marble
What is
Metamorphic calcareous rock composed chiefly of calcite or dolomite; usually granoblastic texture
Is called a what
Migmatite
What is
A mixed rock composed of dark schistose or gneissic parts that are intimately intermingled with light colored igneous looking parts
Is called a what
Quartzite
What is
Metamorphic rock composed dominantly of quartz; distinguished from sandstone in that fractures propagate through quartz grains
Is called a what
Metapelite
What is a
Metamorphic siliceous rock containing abundant micas (muscv. biot.); strictly, should contain an Al-Silicate mineral (andalusite, kyanite, or sillimanite) to demonstrate Al-rich composition equivalent to that of shale (i.e. it is pelitic)
Is called a what
Serpentinite
What is
Metamorphic rock of ultramafic composition composed chiefly of serpentine; may also contain talc, chlorite, and carbonate, as well as relict pyroxene or olivine
Is called a what
Vesicular
What texture is
A rock texture that contains numerous holes that were once occupied by a gas phase
Is what texture
Amygdular
What texture is
A rock texture that has had its vesicles refilled with a material (commonly Calcite, Zeolite, or Quartz)
Is what texture
Pumiceous
What texture is
A rock texture where over 50% of the rock contains abundant vesicles and the rock has a density less than 1 (it floats)
Is what texture
Scoraceous
What texture is
A rock texture where over 50% of the rock contains abundant vesicles and the rock has a density greater than 1 (it sinks)
Is what texture
Graphic
What texture is
A rock texture containing intergrowths of quartz and alkali feldspars wherein the orientation of quartz grains resembles cuneiform writing
Is what texture
Spherulitic
What texture is
A rock texture, common in glassy rhyolites, where glass is replaced by devitrification by spherical growths of quartz and feldspar
Is what texture
