amphibolite
Dark metamorphic stone
Amphibolite is a metamorphic rock composed mainly of amphibole minerals and plagioclase feldspar.
It typically forms when basalt or other mafic rocks are subjected to moderate heat and pressure deep in the earth's crust.
The rock is usually dark green to black, with a coarse-grained texture: The geologist identified the sample as amphibolite based on its mineral composition.
Calcium-iron amphibole mineral
- garnetRed semiprecious stone
- pyroxeneRock-forming silicate group
- biotiteIron-rich layered silicate
- quartzCrystalline silicon dioxide
feldspar · silicate · crystal · texture · lineation · olivine · muscovite · titanite
Foliated metamorphic rock
- schistPlaty-mineral metamorphic rock
- faciesDiagnostic facial appearance
- progradeSame direction as primary
- retrogradeMoving in reverse direction
regional · contact · pressure · temperature · recrystallization · foliation · banding · solid-state
Plate descending beneath another
- orogenyGeological mountain formation
- continentalOf a continent
- oceanicOf the sea
- lithosphereCrust plus upper mantle
mantle · tectonics · seismic · collision · mountain building · craton · terrane
hornblende
Calcium-iron amphibole mineral
quartz · feldspar · silicate · crystal · texture · lineation · olivine · muscovite · titanite
gneiss
Foliated metamorphic rock
- schistPlaty-mineral metamorphic rock
- faciesDiagnostic facial appearance
- progradeSame direction as primary
retrograde · regional · contact · pressure · temperature · recrystallization · foliation · banding · solid-state
subduction
Plate descending beneath another
- orogenyGeological mountain formation
- continentalOf a continent
- oceanicOf the sea
lithosphere · mantle · tectonics · seismic · collision · mountain building · craton · terrane
basalt
Fine-grained volcanic stone
intrusive · dike · sill · plutonic · andesite · diabase · oceanic crust · seafloor · greenstone