Minerals & Igneous Rocks

Question 1

What defines a mineral?

Answer 1

• Naturally occurring
• Definite chemical composition
• Solid
• Crystalline structure
• Inorganic

Question 2

What is the formation of minerals?

Answer 2

• From magma
• During metamorphism
• From a solution

Question 3

Define luster

Answer 3

The way light interacts with the surface of a mineral

Question 4

Define streak

Answer 4

The color of a mineral when it is powdered (ground up)

Question 5

Define cleavage

Answer 5

The way a mineral breaks along planes of structural weakness

Question 6

Define fracture

Answer 6

General breakage of a mineral

Question 7

Define crystal habit

Answer 7

The external shape of a mineral or how it grows

Question 8

What is a rock?

Answer 8

A naturally occurring, cohesive aggregate of one or more minerals; the basic unit that makes up the solid earth

Question 9

What holds sedimentary rocks together?

Answer 9

Various cements

Question 10

What holds igneous & metamorphic rocks together?

Answer 10

They’re held together throughinterlocking crystals

Question 11

What characteristics should you look for when identifying rocks?

Answer 11

• Grain size/texture
• Mineral composition
• Color
• Layering

Question 12

What is an igneous rock?

Answer 12

A rock formed by the solidification & crystallization of a cooling magma or lava

Question 13

What is an extrusive igneous rock?

Answer 13

Volcanic, cools quickly at the surface. Seen in lava flows & pyroclastic debris

Question 14

What is an intrusive igneous rock?

Answer 14

Plutonic, cools slowly under the Earth’s surface

Question 15

What are the two main ways to classify igneous rocks?

Answer 15

• Texture
• Mineral composition

Question 16

What is phaneritic textures?

Answer 16

• Coarse grains ; visible to the naked eye
• Forms from magmas that cool slowly

Question 17

What are aphanitic rock textures?

Answer 17

• Very fine grains; not visible to the eye
• Forms from lavas that cool quickly

Question 18

What is vesicular textures ?

Answer 18

• Gas/bubble -rich lava froze solid before the - bubbles could escape
• Volcanic
• Fast cooling

Question 19

What is glassy rock textures?

Answer 19

• Forms when lava freezes too quickly for any - minerals to form
• Volcanic
• Very fast cooling

Question 20

What is fragmental rock textures?

Answer 20

• Composed of fragments of solid volcanic rocks ejected from a volcano, such as ash, rocks, & minerals
• Volcanic
• Very fast cooling

Question 21

Define felsic minerals

Answer 21

• Light in color
• Not very dense
• High amounts of silica

Question 22

Define mafic minerals

Answer 22

• Dark in color
• dense
• low amounts of silica

Question 23

What are sedimentary rocks?

Answer 23

• They form at Earth’s surface
• Cover underlying basement rock
• Tell us about Earth’s history

Question 24

What is clastic sedimentary rocks?

Answer 24

Loose rock/fragments cemented together & formed by mechanical or chemical breakup of other rocks

Question 25

How are clastic sedimentary rocks formed?

Answer 25

1. Weathering 2. Erosion 3. Deposition 4. Cementation

Question 26

Define weathering

Answer 26

Pre-existing rocks are broken down physically or chemically

Question 27

What are chemical sedimentary rocks?

Answer 27

Minerals precipitated from water

Question 28

What are biochemical sedimentary rocks?

Answer 28

Chemical components from water or sediments derived from living organisms (like fossils)

Question 29

What are organic sedimentary rocks

Answer 29

Made of organic carbon

Question 30

Define metamorphic rock

Answer 30

Solid state alteration of a protolith

Question 31

What changes do we see in metamorphic rocks?

Answer 31

- Shape of rock & internal features - Grain size changes via recrystallization - Minerals react with each other to form new, different minerals through process of neocrystallization

Question 32

Why are there metamorphic changes?

Answer 32

- Temperature - Pressure - Water - Fault movement

Question 33

Define facies

Answer 33

Group of minerals formed at specific p&t conditions

Question 34

Define foliation

Answer 34

Layered metamorphic rock developed by alignment of platy minerals or creation of alternating light/dark bands

Question 35

Define non-foliated

Answer 35

No orientation or alignment of minerals in the rock

Question 36

What are causes of metamorphism?

Answer 36

- Heat (contact metamorphism) - Pressure (regional metamorphism) - Compression & shear from faults (dynamic metamorphism) - Hydrothermal activity

Question 37

Define thermal metamorphism

Answer 37

Only occurs near heat source like: - From magma - Geothermal gradient

Question 38

What is regional metamorphism?

Answer 38

Happens over a broad area of the crust

Question 39

What is dynamic metamorphism?

Answer 39

Deformation of rock at a fault zone at depth (10-15 km)

Question 40

What is hydrothermal metamorphism?

Answer 40

Alteration by hot, chemical laden water ( mid-ocean ridge setting)

Question 41

What is shock metamorphism?

Answer 41

Meteorite impact