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Geology > lab test one > Flashcards

lab test one Flashcards

1
Q

phaneritic texture

A

coarse grained

mineral grains are large enough to see with unaided eye

intrusive texture

magma cooled slowly to allow for crystals to grow

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2
Q

vesicular/ frothy

A

lava contained large amounts of gas (like CO2)

extrusive

lava cooled so quickly that no minerals could form

will most likely have felsic composition

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3
Q

physical/mechanical weathering

A

processes that break rock without changing its chemical composition or properties

ex. frost wedging + heat expansion

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4
Q

medium grained

SIZE

A

detrital

sand-sized

grains between 1/16 mm and 2 mm

grains can be angular or rounded

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5
Q

oolitic texture

A

chemical

composed of rounded oolites

oolites are made of calcite

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6
Q

two types of foliation

A

layered or banded

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7
Q

metallic characteristics

A

shiny?

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8
Q

ign. intrusive textures definition

A

rocks that form from magma that cools below the surface

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9
Q

felsic

A

Minerals: Potassium Feldspar, Quartz, Biotite, Muscovite

Color: Pinkish, Red, White, Light Gray (Also, rocks with a glassy texture of all colors)

SiO2 Content: High

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10
Q

mafic

A

means iron + magnesium

Minerals: Ca-Plagioclase, Pyroxene (Augite), Olivine

Color: Black, Faded Black, Red (vesicular only)

SiO2 Content: Low

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11
Q

tectonic environments

A

subduction zones + riffs/hot spots

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12
Q

riffs/hot spots

A

mafic rocks

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13
Q

what makes a rock sedimentary?

A

form from the accumulation of sediments

sediments are generally formed through some weathering process

  • the only rocks with fossils in them
  • provide geological records
  • chairs, gas, etc.= fossil fuels
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14
Q

chemical weathering

A

chemical processes that cause chemical changes that break down rock

ex. dissolution + oxidation

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15
Q

detrital texture characteristics

A

compromised of mineral fragments held together by cement

textures are described based on their particle size

  • coarse grained
  • medium grained
  • fine grained
  • very fine grained
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16
Q

fine grained

SIZE

A

“fine grained/silt sized”

detrital

silt-sized grains; between 1/256 mm and 1/16 mm

will often feel smooth to skin but rough to fingernail

often the mineral quartz

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17
Q

crystalline texture

A

chemical

compromised of crystals large enough to distinguish with the eye

composed of minerals softer than glass

*calcite, gypsum, hallite

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18
Q

foliation

A

indicates that metamorphism has affected rocks

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19
Q

what makes it a mineral?

A

must be five things

  1. solid
  2. naturally occurring
  3. inorganic (usually)
  4. definite but not fixed, chemical composition
  5. ordered internal arrangement (crystalline structure)
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20
Q

what is color?

A

simply the color you see when you observe a sample

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21
Q

be able to explain what “streak” is and why it is important

A

color that a powdered sample has.

light can transmit through the small powder particles

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22
Q

luster

A

a minerals appearance when light is reflecting off its surface

two main categories

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23
Q

luster’s two main categories

A

metallic vs. non metallic

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24
Q

non-metallic characteristics

A

glass, pearly, dull, fibrous

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25
Q

striations

A

look like small parallel lines etched into a minerals face

caused by mineral twinning

you may not be able to see it in all samples of minerals that have striations

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26
Q

hardness

A

a materials resistance to being scratched

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27
Q

tenacidy

A

when the material is hit

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28
Q

cleavage

A

what a mineral does when it breaks upon a plane of weakness

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29
Q

1-direction cleavage

A

basal, sheety

@ 90 degrees= blocky
not @ 90= splinters, oblique cleavage

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30
Q

3-direction cleavage

A

@ 90 degrees= cubic

not @ 90= rhombic

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31
Q

4-direction cleavage

A

octahedral

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32
Q

6-direction cleavage

A

dodecahedral

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33
Q

know each of the physical property tests, how they work, how to do them, and what they tell about the mineral being tested

A

Moh’s scale of hardness (fingernail, glass test, acid test)

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34
Q

be able to recognize and identify “special” properties

A

10

smell
taste
acid reaction
magnetism
feel
flexibility
elasticity
conchodrial feature (vs. uneven)
striations
high density
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35
Q

what is a rock?

A

a solid aggregate of minerals

with a few minor exceptions, a rock consists of pieces of mineral material held together in some fashion

36
Q

what makes a rock igneous?

A

rocks that form from the cooling of a melt

consists of interlocking crystals of minerals that form while these melts cool
these crystals can be large enough to see or may require a microscope + a thin section of the rock

  • no layering or foliation
  • mainly composed of silicate minerals, therefore almost always dense and hard
37
Q

geologists name melts based on _________

A

their relation to the surface

below: magma
at or above: lava

38
Q

rock textures

A

texture= important
has nothing to do with how the rock “feels”

describes:
grain shape
grain size
grain orientation

39
Q

ign. extrusive textures definition

A

rocks that form from lava that cools at or above the surface

40
Q

examples of intrusive textures

A

pegmatitic
phaneritic
porphyritic

41
Q

examples of extrusive textures

A 
aphanitic
porphyritic
glassy
vesicular
fragmental/pyroclastic
42
Q

pegmatitic texture

A

very large crystals (some may be >2 cm. in size)

intrusive texture

magma contained large amounts of fluid (water or CO2)

if a number of the crystals are the size of two finger widths, then the rock can be classified as pegmatitic

43
Q

aphantic texture

A

fine grained

mineral grains are too SMALL to be see with the unaided eye

extrusive texture

lava cooled relatively quickly + crystals do not have to grow very large

44
Q

porphyritic texture

A

often a mixture of fine + coarse grained

2 different (at least) sized mineral grains

intrusive/extrusive textures

magma/lava cooled at different rates resulting in crystals of different sizes

phenocrysts + groundmass

45
Q

phenocrysts

A

longer crystals that cooled before the rest of the rock

46
Q

groundmass

A

smaller crystals that formed as the rest of the magma cooled

47
Q

glassy texture

A

no mineral grains to be seen

extrusive textures

lava cooled so quickly that no minerals could form

will most likely have felsic composition

48
Q

fragmental (pyroclastic)

A

rock made up of fragments of volcanic glass, mineral crystals, or lithic (rock) fragments. much of the rock is ash

extrusive

usually associated with violent volcanic eruption

49
Q

intermediate

A

Minerals: Na/Ca- Plagioclase Feldspar, Biotite, Amphibole (Hornblende)

Color: Medium to Dark Gray

SiO2 Content: Intermediate

50
Q

ultramafic

A

Will not see in lab. Rare on Earth’s Surface

makes up the Earth’s surface

Minerals: Ca-Plagioclase, Pyroxene (Enstatite), Olivine

Usually comprised of over 80% of one of the above minerals.

Color Varies based on mineral composition.

51
Q

three types of volcanoes and examples of each

A

shield: ex. Marina Coa
cindercone: ex. Capulin Volcano, New Mexico

stratovolcano (composite): ex. Mt. Saint Helens

52
Q

shield volcano

A

curved, with curve facing the sky/convex

typically not as dangerous?

very wide + large

usually composed of MAFIC material

53
Q

cindercone volcano

A

much smaller, but can grow very quickly

only about 1000 feet high

usually composed of MAFIC material

54
Q

stratovolcanoes (composite)

A

medium in size

only a few 1000 feet high; typically 5-6,000

usually medium gray

usually composed of INTERMEDIATE material

EXPLOSIVE ERUPTIONS

55
Q

subduction zones

A

felsic rocks always form here

intermediate

56
Q

two types of weathering

A

physical/mechanical

chemical

57
Q

chemical or organic texture characteristics

A

compromised of accumulations of shells., precipitated minerals, + other chemical sediments

textures are related to various appearances

  • crystalline + microcrystalline
  • fossiliferous + microfossiliferous
  • oolitic
  • carbonaceous
58
Q

examples of detrital textures

A

5
angular/coarse-grained

rounded grained

medium grained

fine grained (silt-sized)

very fine grained

59
Q

examples of chemical textures

A

crystalline

microcrystalline

fossiliferous

microfossiliferous

oolitic

60
Q

example of organic texture

A

carbonaceous

61
Q

(SIZE) coarse-grained/(SHAPE) angular characteristics

A

detrital

gravel-sized

grains are larger than 2 mm in size

little to no rounding on grains

*just like taking a hammer to a rock + gluing the pieces together

62
Q

rounded grained characteristics

SHAPE

A

detrital

gravel-sized

grains are larger than 2 mm in size

grains show considerable rounding; no sharp angles

63
Q

very fine grained

SIZE

A

detrital

clay-sized grains

smaller than 1/256 mm

will feel smooth to skin AND fingernail

both a size and type of mineral

64
Q

microcrystalline texture

A

chemical

crystals too small to see with eye

composed of clay-sized chemical sediments

either composed of quartz or calcite

65
Q

fossiliferous

A

chemical

compromised of either whole or broken fossils, large enough to see

fossils will be made of calcite

66
Q

microfossiliferous

A

chemical

compromised of fossils to small to see w/ eye

will have powdery feel

composed of calcite

67
Q

carbonaceous texture

A

organic

compromised of carbon- not actually made of minerals

may have glassy or blocky appearance

68
Q

two depositional environments of sedimentary rocks

A

terrestrial + marine

69
Q

terrestrial environment characteristics

A

gravels

rusty red colors

salt deposits

carbonaceous material or plant fossils

70
Q

marine environment characteristics

A

greens, blacks, tans, browns
UNLESS it has salt

any rock made of calcite
(crystalline, microcrystalline, fossiliferous, microfossiliferous, oolitic)

microcrystalline quartz, regardless of color

71
Q

what makes a rock metamorphic?

A

harder/denser/heavier than igneous + sedimentary rocks

likely to possess foliation

rocks more brittle (if fine grained like shale, will be more brittle than shale)

may possess a “sheen” due to foliation

may have grains that are flattened or “oval” shaped because of pressure lack fossils

usually lack the granular cemented nature of sedimentary– more likely to have interlocking crystals. but crystals may be aligned

72
Q

examples of metamorphic rock

A 
talc
chlorite
saturolite
garnet
kyanite
73
Q

sheen vs. no-sheen

A

sheen: a soft luster on a surface

74
Q

layered foliation

A

in metamorphic rocks, is common in rocks of low to middle grades of alteration

75
Q

banded foliation

A

essentially always related to high intensity alteration and found almost exclusively in high grade metamorphic rocks

76
Q

foliated textures

A

will have foliated layers or foliation bands

fine-grained
fine-grained w/ sheen
coarse grained

77
Q

non-foliated textures

A

will not have foliated layers or bands

fine-grained
coarse-grained
glassy/blocky

78
Q

metamorphic grade

A

only applied to foliated rocks

different intensities of metamorphism
when heat, pressure, + chemical action alter the rocks

79
Q

low metamorphic grade

A

fine grained/ fine w/ sheen

layered foliation

increase in crystal size with increasing metamorphism

suggests that rocks with smaller/finer grains have undergone less intense alteration

80
Q

minerals found in metamorphic rocks

A 
talc
garnet (sometimes igneous)
chlorite (green)
staturolite
aluminosilicates
81
Q

what are the aluminosilicates?

A

sillimonite
andalusite
kyanite (blue)

82
Q

important changes in metamorphic rocks

A

change in grain size (larger)

change in grain orientation

change in rock mineralogy

change in rock density

83
Q

medium grade in met. rocks

A

coarse grained

layered foliation

84
Q

high grade in met. rocks

A

coarse grained

banded foliation

85
Q

foliated

A

(very) fine grained

fine grained w/ sheen

coarse grained- medium

coarse grained- high

86
Q

non-foliated

A

crystalline

  • quartz= scratch glass
  • dolomite/calcites- size

glassy/greasy
-carbon

Geology (6 decks)

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