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Earth Sciences > 5. Earth Materials and Minerals > Flashcards

5. Earth Materials and Minerals Flashcards

1
Q

What are minerals? (3)

A

a) naturally occurring solids with b) fixed chemical composition
c) periodic array of atoms forming crystal structure

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2
Q

How many minerals are there? How many did we start off with? How did more become?

A

4000 known species
pre-solar nebula only had 12
more formed because of incongruent melting

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3
Q

What are sediments?

A

pieces of weathered rocks and minerals (boulders, cobbles, pebbles, sand, silt, mud, clay, nanoparticles)

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4
Q

What are melts?

A

molten rocks

no ordered arrangement of atoms

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5
Q

What are glasses?

A

frozen melts

no ordered arrangement of atoms

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6
Q

What are quartz?

A
  • naturally occurring mineral
  • the name tells the phase: SIO2 and trigonal symmetry
  • fixed chemical composition
    periodic arrangement of atoms
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7
Q

What is a phase?

A

a combination of composition and structure

- ex- quartz is SiO2 and trigonal symmetry

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8
Q

How many phases does SiO2 have?

A

7 phases (a-quartz, b quartz, tridymite, cristobalite, coesite, stihovite, liquid, )

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9
Q

What is an igneous rock and how do we classify them?

A

a rock that has crystallized from a melt

- classify based on silica content and extrusive/ intrusive

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10
Q

What is an intrusive/ extrusive igneous rock?

A
  • intrusive/ plutonic- rocks that cooled slowly in earth’s crust. Have large crystals and coarse grained. Ex- granite
  • extrusive- rocks that cooled quickly near or on surface of earth in volcanic eruptions. Fine grained. Ex- rhyolite
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11
Q

Do extrusive and intrusive igneous rocks have the same composition?

A

Yes

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12
Q

What is metamorphism?

A
  • when rocks undergo solid-state changes that are enhanced by hot, mineral rich fluids
  • any rock can be metamorphosed, making them different from origin rock
  • ex- silica-rich igneous rocks (granite) or sediments metamorphones into gneiss . We see banding dark and light colors
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13
Q

What’s an example of metamorphism?

A
  • silica-rich igneous rocks (granite) or sediments metamorphones into gneiss We see banding dark and light colors
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14
Q

What is granite?

A
  • intrusive igneous rock
  • high in silica content (felsic)
  • in crust
  • most commonly made up of alkali feldspar. Also contains plagioclase feldspar, quartz, and mica
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15
Q

What is rhyolite?

A
  • extrusive igneous rock
  • high in silica content (felsic)
  • made of quartz, alkali feldspar, plgioclase feldspar
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16
Q

Are melts and glass minerals?

A

No

17
Q

What’s the oldest stone tool?

A

2.5 Ma old

18
Q

Give an example of how mineral diversity changed by life.

A
  • trilobites grew calcite shells. Became survival tools
  • humans grow apatite mineral in bones and enamel
  • early bacteria got energy from minerals
19
Q

What are the stages of earth and what are the dates?

A 
Black Earth- 4.5
Grey Earth- 4.3
Blue Earth- 3.8
Red Earth- 3.5
White Earth- 540 Ma
Green Earth- 520 Ma- now
20
Q

What was the black earth?

A
  • 4.5 Ma
  • dust and rocks just accreted
  • magma ocean cooling, leaving black basaltic surface
21
Q

What was the grey earth?

A
  • 4.3 Ma
  • incongruent melting gave way to granite
  • zircons still found today in Australia (4.4) and Canada (4.2)
22
Q

What was the blue earth?

A
  • 3.8
  • first known water was stable turned planet blue with oceans
  • we know the age because pillow basalts off Greenland were 3.8 Ga and formed underwater
23
Q

What was red earth?

A
  • 3.5 Ga
  • cynobacteria (First photosynthesizing forms of life) pumped oxygen into air, seas
  • oxidizing all minerals in seas, rained down, forming banded iron formations
24
Q

What was the white earth?

A
  • 540 Ma
  • continents coming together, moving apart meant climate changing a lot
  • snowball conditions- glacial deposits, lots of ic
25
Q

What is green earth?

A
  • 520 Ma- present

- explosion of diversity

26
Q

What are the most common elements in the crust?

A

Oxygen, Silicon, Aluminum (most to least)

27
Q

What is the most abundant mineral in the crust? What are its 2 parts?

A
  • feldspar (Al, Si, O), an aluminosilicate
  • plagioclase feldspar (Ca, Na)- basalt
  • alkali feldspar (Na, K)- granite
28
Q

Feldspar is a what?

A

aluminosilicate

29
Q

What is a plagioclase feldspar?

A

Feldspar made of Calcium and Sodium

Most common mineral in basalt

30
Q

What is an alkali feldspar?

A

Feldspar made of potassium and soldium

Most common mineral in granite

31
Q

Which is easier to decompose and what does it decompose into? Quartz or feldspar?

A
  • feldspar
  • Na, K, Ca rich clays, transform into soil
  • all of our soil is from weathered crystals of feldspar rocks
  • quartz is more resistant to weathering
32
Q

What is the second most abundant mineral in the crust?

A

Quartz

33
Q

Name the silica content and give examples

A 
crust
>60% felsic, granite, rhyolite
50-60% intermediate
45-50% mafic, basalt
<45% ultramafic, peridotite 
mantle
34
Q

Why do we choose to use silica content?

A

Because as magma rises from mantle to crust, it increases in silica content via incongruent melting.

Earth Sciences (15 decks)

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