Geol 1121 Lab Exam 1

Front 1

Form when magma or lava cool to a solid form, either glass or masses of intergrown mineral crystals. The crystals are large if they had a long time to grow in a slow cooling environment and are small if they formed quickly in a rapidly cooling lava.

Back 1

Igneous Rocks

Front 2

Form mostly when mineral crystals and clasts of plants, animals, mineral crystals, or rocks are compressed or naturally cemented together. Also form when mineral crystals precipitate from water to form a rocky mass such as rock salt or stalactites.

Back 2

Sedimentary Rocks

Front 3

Deformed rocks that have changed from one form to another via intense heat, pressure and/or the actions of hot fluids. This causes the rock to recrystallize, fracture, change color or flow. As the rock flows, the flat layers are folded and the mineral crystals are aligned like parallel needles or scales.

Back 3

Metamorphic Rock

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Grains less than 1 mm and unidentifiable with naked eye

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Fine grained

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Grains larger than 1 mm and identifiable with naked eye

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Coarse grained

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Rocks that are oriented or lined up into patters or layers that cause the rock to break or reflect light in a specific direction like the scales on a fish

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Foliated

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Occurs when all the mineral crystals in a rock are all about the same size

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Equigranular

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Texture of rocks that contain grains that are clasts of minerals, other rocks, plants or animals

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Clastic

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The hardening of sediment

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Lithification

Front 10

Produces crystals that collect in aggregates when water evaporates

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Precipitation

Front 11

Inorganic, naturally occurring substances hat have a characteristic chemical composition, distinctive physical properties and crystalline structure.

Back 11

Minerals

Front 12

Main minerals observed in rocks

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Rock-forming minerals

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Main minerals used to manufacture physcal materials of industrialized societies

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Industrial minerals

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Minerals that can be manufactured by organisms

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Biochemical Minerals

Front 15

The general crystal forms and combinations in which a mineral habitually forms

Back 15

Crystal habit

Front 16

A description of how light reflects from the surface of an object; metallic or nonmetallic.

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Luster

Front 17

Resembling the luster of freshly broken glass or a glossy photo

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Vitreous

Front 18

Resembling the luster of a candle

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Waxy

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Resembling the luster of a pearl

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Pearly

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Lacking reflection, completely dull like dry soil

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Earthy

Front 21

Resembling the luster of grease; oily

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Greasy

Front 22

Refers to the color of a substance after it has been ground to a powder

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Streak

Front 23

A measure of resistance to scratching

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Hardness

Front 24

The tendancy of some minerals to break along flat, parallel surfaces.

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Cleavage

Front 25

Any break in a mineral that does not occur along a cleavage plane

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Fracture

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Glass-like fracture along ribbed, smoothly curved surfaces

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Conchoidal fracture

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The manner in which a substance resists breakage

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Tenacity

Front 28

Straight, hair-like grooves on the cleavage surfaces of some minerals.

Back 28

Striations

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The density of a substance divided by the density of water.

Back 29

Specific Gravity

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The initial formation of microscopic crystal, to which additional atoms progressively bond

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Nucleation

Front 31

Rapid cooling of very viscous magma (with poor nucleation) produces rocks with...

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Glassy texture

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Texture of igneous rocks made of crystals <1mm that are unidentifiable with the naked eye

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Aphanitic

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Texture of igneous rocks made of crystals 1-10mm that are visible and identifiable with the naked eye

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Phaneritic

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Texture of igneous rocks with crystals larger than 1 cm

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Pegmatitic

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Texture of igneous rocks with two distinct sizes of crystals; Larger crystals (pheocrysts) and smaller, more numerous crystals (groundmass or matrix)

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Porphyritic

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Texture that occurs when gas bubbles get trapped in cooling lava

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Vesicular

Front 37

Eight minerals that make up most Igneous rocks

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1. quartz - gray
2. plagioclase feldspar - light grey
3. potassium feldspar - light orange to pink
4. muscovite - pale
^^^ felsic/silicates^^^
5. biotite - glossy black
6. amphibole - dark grey to black
7. pyroxene - dark green to gray
8. olivine - green
^^^mafic/mg and fe^^^

Front 38

Bowens reaction series

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Series that predicts the order of crystallization of mafic minerals. Olivine --> pyroxene --> amphibole/biotite --> Muscovite --> quartz
Continuous series: Plagioclase (Ca) feldspare --> K-spar

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Decomposition or dissolution of earth material.

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Chemical weathering

Front 40

Forms when aqueous solutions full of dissolved chemicals evaporate and the chemical combine to precipitate mineral crystals and amorphous residues

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Chemical sediment

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The cracking, crushing and wearing away of earth material.

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Physical weathering

Front 42

Forms when cracking and crushing occurs and causes big rocks to be fragmented into clasts.

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Clastic sediment

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Forms when fragmented plants and animals occur in a rock

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Biochemical sediment

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Forms when scratching and abrasion of grains and bedrock surfaces wears away sediment from land and rounds sharp edges of individual grains

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Detrital sediment

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Wentworth grain scale

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Classifies common grain sizes in sedimentary rocks:
Gravel - big pieces and pebbles
Sand - visible and gritty grains
Silt - invisible, but still feels gritty
Clay - invisible and smooth

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Structure with clearly visible crystals

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crystalline structure

Front 47

Structures with invisible crystals

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microcrystalline

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Surfaces between strate

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Bedding planes

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Formed from sediment being transported in a single direction by water or air currents

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current ripple marks

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Formed from sediment being transported by back and forth water motions or very gentle waves skimming the bottom of a lake or ocean

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oscillatory ripple marks

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Occurs if a sequence of cross strata is inclined in opposite directions

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bimodal cross bedding

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Caused by sediment laden currents suddenly slow as they enter a standing body of water or as current flow terminates abruptly

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Gradation

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Scoop shaped v - depression scoured into a sediment surface by the erosional, winnowing action of currents

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Flutes

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Sediment filled futes

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Flute casts

Front 55

Form when deposits of mud dry and shrink

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Mud cracks