Rock Practical Flashcards
What are the 3 main rock types?
Igneous, Sedimentary, metamorphic
What are igneous rocks characterised by?
Crystalline structures
What are the two characteristics igneous rocks are classified by?
- Crystal size
- Mineralogy (whether its felsic, intermediate, or mafic)
What does the crystal size of igneous rocks tell us about the environment in which they were made?
Temperature/depth
fine crystals = quick cooling near the surface
coarse crystals = slow cooling deeper down
How can we tell whether an igneous rock is more mafic or felsic? What does this tell us about their formation?
Darker colours = more mafic (formed first)
Lighter colours = more felsic (formed later)
What are the two types of material sedimentary rocks can be formed from?
- material eroded from other rocks, transported and deposited (clastic)
- Formed from organic material or chemical precipitates
Name four types of clastic sedimentary rocks?
Breccia, Mudstone, Siltstone, Sandstone
Order these four clastic sedimentary rocks from finest to coarsest.
Breccia, Mudstone, Siltstone, Sandstone
Fine: Mudstone, Siltstone, Sandstone, Breccia :Coarse
Name 3 chemical sedimentary rocks.
Oolite, Dolomite, Chert, Rock salt, Gypsum
Name 3 biochemical sedimentary rocks.
Fossiliferous limestones, Micrite, Silicious, Carbonaceous, Chalk.
What is a metamorphic rock?
Rocks altered by heat, pressure, and/or reactive fluids.
What does a limestone become when metamorphised?
Marble
What are the stages of metamorphising shale?
Shale -> Slate -> Schist -> Gneiss
Name 2 coarse grained igneous rocks? Which is more felsic?
Granite, diorite
Granite is more felsic (lighter)
