Lab 3 // Igneous Rocks Flashcards

1
Q

Granite

A
Texture: phaneritic
Minerals/Groundmass: potassium feldspar, Na-rich plagioclase, quartz, biotite
Rock type: felsic
Processes:
-low temperature
-intrusive
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2
Q

Granodiorite

A
Texture: phaneritic
Minerals/Groundmass: Na-rich plagioclase, quartz, biotite
Rock type: felsic
Processes:
-low temperature
-intrusive
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3
Q

Basalt

A
Texture: aphanitic
Minerals/Groundmass: black groundmass
Rock type: mafic
Processes:
-high temperature
- extrusive / intrusive
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4
Q

(porphyritic) Dacite

A

Texture: (porphyritic) aphanitic
Minerals/Groundmass: light grey groundmass with amphibole phenocrysts
Rock type: felsic
Processes:
-low temperature
-intrusive or intrusive
- two stages of cooling - slow first forming the phenocrysts and then fast to form the groundmass

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5
Q

(porphyritic) Rhyolite

A

Texture: aphanitic / porphyritic
Minerals/Groundmass: light pink groundmass / red groundmass with quartz phenocrysts
Rock type: felsic
Processes:
-low temperature
-intrusive or intrusive
- two stages of cooling - slow first forming the porphyritic sample

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6
Q

Diorite

A
Texture: phaneritic
Minerals/Groundmass: mainly amphibole and Na-rich plagioclase
Rock type: intermediate
Processes:
-intermediate temperature
-intrusive
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7
Q

Peridotite (olivine)

A
Texture: phaneritic
Minerals/Groundmass: olivine
Rock type: ultramafic
Processes:
-very high temperature
-intrusive (earth's mantle)
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8
Q

Scoria (vesicular basalt)

A

Texture: aphanitic and vesicular
Minerals/Groundmass: rusty red (oxidized) groundmass
Rock type: mafic
Processes:
-high temperature
-extrusive (with gas escaping to form the vesicles)

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9
Q

Gabbro

A
Texture: phaneritic
Minerals/Groundmass: mostly Ca-rich plagioclase (striations), minor pyroxene (dull black)
Rock type: mafic
Processes:
-high temperature
-intrusive
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