Name
Chapter 6 Rocks
NOTES 6.2 Igneous Rocks Pgs. 121 - 126
1. Igneous Rock Formation
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
Form from the __________________ of molten rock
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_______________________ (volcanic)- form at or near the surface from lava
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Intrusive (_______________) – form under the surface from magma
Igneous rocks are classified by ____________________ composition
(mafic or felsic) and __________________

Texture
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____________, shape and arrangement of grains (______________)
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Grain or crystal ___________ depends on:
o ________________ of cooling
 Fast = ______________
 ________________ = large
o ___________________ _____________
 More = _______________
o Order of solidification
2. The Starting Material

Magma is classified as Felsic, Mafic or Intermediate
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Felsic

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_______________ colored
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___________ silica magma with abundance of quartz and feldspar.
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_______________ slow flowing in molten state.
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Most __________________ rocks.
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Acidic
Mafic
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________________ colored,
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Low silica ferromagnesian magma
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More __________________ than felsic magma.
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Most ____________________ igneous rocks.
3. Underground Magma

Magma can cool slow or fast depending on ____________ cooling occurs
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Intrusive rocks cool very __________________ underground
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Result of slow cooling
o _______________ (large) grains
4. At the Surface
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
Magma pouring onto the surface is called ____________
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Extrusive igneous rocks cool ________________
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_______________________ grains or none at all
Porphyry
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Rocks that cool ________ underground and at the _______________
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Results in _____________ and ____________ grains
5. Igneous Families

Grouped according to ___________________ _____________________

_________________ is determined where it cools - intrusive or extrusive
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Each family can have coarse grained, fine grained or glassy textures
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Also can have ______________________
o Vesicles are ________ cavities within the rock

Granite family
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______________ magma
-
___________ colored
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Quartz and Feldspar
o Coarse
 ________________
o Fine
 ________________
o Glassy
 ________________ and __________________

Gabbro Family
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Mafic magma
-
_______________ colored
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Pyroxene and ________________
o Coarse
 ________________
o Fine
 ________________
o Vesicular
 ________________

Diorite family
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Intermediate
o Coarse
 Diorite
o Fine
 Andesite
6. Igneous Intrusions

____________________– a rock mass that forms when magma cools
under ground
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Dikes
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_________________
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_____________________
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Volcanic necks
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_____________________ – largest of all plutons, form the cores of
most mountains