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Flashcards in ROCKS Deck (88):
1

Define Rock

naturally occurring solid mixture of one or more minerals or organic matter

2

how are rocks classified?

1. how they are formed
2. composition (what they are made of)
3. texture

3

Rocks change over time via what?

Rock Cycle

4

what are the three types of rocks

igneous, sedimentary, metamorphic

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igneous rocks form from what

cooled liquid magma

6

Any rock can become an igneous rock if

it's melted into magma

7

when magma reaches earth's surface, it is called

lava

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We identify igneous rocks by...

texture and color

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how many types of texture?

four

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how is texture determined?

how quickly a rock cools

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the cooling rate determines what

the size of the minerals within the rock

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texture describes what two things..

crystal size and appearance

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What are the 4 types of texture (by speed of cooling)

pyroclastic (fastest)
froth
fine-grained
intrusive (slowest)

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What does pyroclastic mean?

Formed by explosion

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what is another word for pyroclastic

fragmental texture

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pyroclastic are the _______ and _______ that are blown into atomosphere

ash and cinders

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because pyroclastic cools so quickly...

no crystals form and ashes and cinders are cemented together

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Froth is magma that is cooled by

water or forced far from the source of heat

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Do crystals form with pyroclastic or froth?

NO

20

the texture of froth is called

glassy or vitrous

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Name another name for volcanic glass

Obsidian

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Pumice, which is not smooth is formed from...

froth

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obsidian is formed from..

froth

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fine-grained is magma that cools..

above the Earth surface

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fine grained magma forms crystals that...

aren't visible

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when crystals are not visible it's called

extrusive

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extrusive rocks have _______ appearance

uniform

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The slowest cooling rocks are called

intrusive

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intrusive rocks cool where

within the Earth

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intrusive rocks have _______ texture

coarse

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what does coarse texture mean?

You can see the crystals that have formed. You may even be able to identify different minerals.

32

depending on where/how a volcano forms, the magma will dissolve a different amount of

silica

33

silica makes up what percent of Earth crust

95%

34

what is another word for silica?

silicon dioxide SiO2

35

magma inside the earth is made primarily of..

..heavy metals

36

amount of Earth's crust dissolved by magma rising to surface is correlated to

amount of silica added to magma

37

felsic rocks are (color)

light in color

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felsic rocks are low in _______ and high in ______

low = heavy metals and high = silica

39

FEL in felsic is for

potassium feldspar

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SIC in felsic is for

silica

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felsic have specific gravity of

less than 3.0

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felsic is lighter because they contain less

metals

43

mafic rocks are (color)

dark

44

mafic rock contain silica but have higher amounts of

heavy metals

45

MA in mafic comes from

magnesium

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FIC in mafic from

Latin word for iron

47

mafic have specific gravity of

more than 3.0

48

intermediate are somewhere between

felsic and mafic

49

Intermediate color is

grey or brown--neither very light or very dark

50

the word intermediate means

in the middle

51

Ultramafic are extremely

DARK and HEAVY

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Ultramafic rocks have very high percentages of

heavy metals

53

Sedimentary rocks from when

bits of sediment are compacted and cemented together

54

to become a sedimentary rock, it first need to be

sediment

55

sedimentary rocks are made of

sediment but can also consist of organic matter compacted/cemented together

56

sedimentary rocks are classified by

rock type, texture and structure

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what are the three types of sedimentary rocks

Clastic/detrital, chemical or organic

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What is a clastic/detrital rock

pre-existed rock compacted/cemented together

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A Clastic or detrital rock can be what sizes

boulder, pebble, sand, silt/clay

60

Chemical sedimentary rock forms how?

when bits of pre-existing rock and minerals are dissolved in a solution (usually sea water) are cemented together as the solution evaporates.

61

Give two examples of chemical sedimentary rock...

rock gypsum and rock salt

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How is organic sedimentary rock formed?

when organic matter is compressed and cemented together.

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Give examples of organic sedimentary rock

coal, limestone, limestone coquina

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How is texture determined

by the visibility of the particles of the rocks

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what is the range of texture?

fine, medium and coarse

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If a rock's texture has uniform color and visible sediments the texture would be

fine

67

if a rock's color is mostly uniform and small particles visible what is texture

medium

68

if a rock is composed of large, obvious particles what is texture?

coarse

69

STructure describes the what of a rock

APPEARANCE

70

If the structure is FRAGMENTAL it means

it is obvious that different types of particles are cemented together

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if the structure of a rock is GRANULAR

it appears to be grainy, composed of sand-sized particles or smaller

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If the structure of the rock is CRYSTALLINE

it means crystal shape is evident in structure of the rock

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if the structure of the rock is GLASSY

it means the rock is shiny or scratchy in appearance

74

if the structure of the rock is RESINOUS

it means the rock appears to contain resin (produced by trees and plants)

75

How do METAMORPHIC rocks form?

when existing rocks of any type are pushed deep within the Earth and are exposed to extreme heat and pressure

76

in METAMORPHIC rocks the heat and pressure

cause partial melting and compression of the existing rock

77

two ways metamorphic rocks are classified

foliated and non-foliated

78

some Metamorphic rocks have a banded appearance which means

the rock has stripes or alternating layers of color

79

foliated rocks often cleave along

their layers

80

non-foliated metamorphic rocks have no

visible layers and often have complete fracture (or do not break along clear surface)

81

what is difference between foliated and non-foliated metamorphic rocks

foliated = layers
non-foliated = no layers

82

Metamorphic rock texture means

the size of visible crystals

83

when no crystals are visible we say

the rock is FINE GRAINED

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when crystals are obvious we say

COARSE GRAINED

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when rocks have a range of crystals--fine to coarse we say

medium grained

86

what is a parent rock?

what rock the metamorphic rock came from i.e. before it was exposed to extreme heat and pressure

87

If we can identify a parent rock of a metamorphic rock we can

make connection between rocks we can identify and visualize the rock cycle process

88

What is the rock cycle?

(look at diagram on study guide)