Chapter 3- Igneous

Question 1

What is the definition of an igneous rock?

Answer 1

An igneous rock is a type of rock formed through the cooling and solidification of magma or lava.

Question 2

True or False: Igneous rocks are classified based on their mineral composition and texture.

Answer 2

True

Question 3

Fill in the blank: Igneous rocks that cool and solidify below the Earth’s surface are called ________ rocks.

Answer 3

Intrusive

Question 4

What is the main difference between intrusive and extrusive igneous rocks?

Answer 4

Intrusive rocks cool slowly beneath the Earth’s surface, while extrusive rocks cool quickly on the surface.

Question 5

What is the most common extrusive igneous rock?

Answer 5

Basalt

Question 6

What is the most common intrusive igneous rock?

Answer 6

Granite

Question 7

Fill in the blank: Igneous rocks are often used in ________ and ________ construction due to their durability.

Answer 7

monument; building

Question 8

What is the term for the process of magma cooling and crystallizing to form igneous rocks?

Answer 8

Solidification

Question 9

True or False: Igneous rocks can be formed from both magma and lava.

Answer 9

True

Question 10

What is the term for the size, shape, and arrangement of mineral grains in an igneous rock?

Answer 10

Texture

Question 11

Fill in the blank: Igneous rocks that are formed from the cooling and solidification of lava are called ________ rocks.

Answer 11

Extrusive

Question 12

What is the term for the process of magma rising and cooling beneath the Earth’s surface?

Answer 12

Intrusion

Question 13

True or False: Basalt is a common extrusive igneous rock with a fine-grained texture.

Answer 13

True

Question 14

What is the term for the process of magma mixing with other rocks and changing composition?

Answer 14

Magma mingling

Question 15

Fill in the blank: Igneous rocks are often classified based on their ________ and ________ composition.

Answer 15

mineral; chemical

Question 16

What is the term for the process of magma cooling and forming crystals within the Earth’s crust?

Answer 16

Crystallization

Question 17

True or False: Pumice is an example of an extrusive igneous rock with a vesicular texture.

Answer 17

True

Question 18

What is the term for the process of magma cooling and forming crystals at the Earth’s surface?

Answer 18

Volcanism

Question 19

Fill in the blank: Igneous rocks that contain a high percentage of quartz are classified as ________ rocks.

Answer 19

Felsic

Question 20

What is the term for the process of magma cooling and forming crystals after eruption?

Answer 20

Post-eruption crystallization

Question 21

True or False: Diorite is an example of an intrusive igneous rock with a medium-grained texture.

Answer 21

True

Question 22

What is the term for the process of magma cooling and forming crystals before eruption?

Answer 22

Pre-eruption crystallization

Question 23

Fill in the blank: Igneous rocks that are rich in iron and magnesium are classified as ________ rocks.

Answer 23

Mafic

Question 24

What is the term for the process of magma cooling and forming crystals within a volcano?

Answer 24

Intravolcanic crystallization

Question 25

Pegmatitic

Answer 25

Extremely course grained (usually under >5 cm), forms when magma cools very slowly

Question 26

Porphyritic

Answer 26

Includes 2 distinct crystal sizes, with the larger *Phenocrysts* having formed first during slow cooling underground and the smaller *ground mass* forming during more rapid cooling at the Earth's surface.

Question 27

Phenocrysts

Answer 27

large crystals that form early in the crystallization of magma and are embedded in a finer-grained matrix in igneous rocks.

Question 28

Glassy texture

Answer 28

Contains no crystals at all and is formed by extremely rapid cooling of the magma.

Question 29

Vesicular

Answer 29

Contains cavities (vesicles) in extrusive rocks resulting from gas bubbles that were in the lava. Scoria and pumice are examples.

Question 30

Pyroclastic texture

Answer 30

Consolidated pyroclastic debris such as ash, pumice or crystalline rock. Tuff and Volcanic Breccia are examples.

Question 31

Intermediate rock

Answer 31

Silica contents between 55% and 65% by weight. Diorite and Andesite are examples.

Question 32

Ultramafic rocks

Answer 32

<45% silica and composed almost entirely of dark-colored (black/green) ferromagnetic minerals. Peridotite and Komatite.

Question 33

Differentiation

Answer 33

Process by which different ingredients separate from an originally homogenous mixture.

Question 34

Crystal setting

Answer 34

Changes magma comp as the crystals are removed from the melt as they settle downwards

Question 35

Partial melting

Answer 35

Process by which the magma composition varies as different minerals/rocks melt at different temperatures.

Question 36

Assimilation

Answer 36

Process whereby a hot magma comp will change as it melts and assimilate adjacent rocks into the magma.

Question 37

Volcanic neck

Answer 37

Shallow intrusion formed when magma solidifies in throat of volcano.

Question 38

Dike

Answer 38

Shallow tabular intrusive structure that cuts across any layering in country rock (web)

Question 39

Sill

Answer 39

Shallow, tabular intrusive structure that parallels layering in country rock. (Lines)

Question 40

Sill

Answer 40

Shallow, tabular intrusive structure that parallels layering in country rock. (Lines)

Question 41

Plutons

Answer 41

Deep, large, blob-shaped intrusive bosy formed of coarse grained igneous rock, commonly granitic in composition.

Question 42

Stocks Batholiths

Answer 42

Small plutons Large plutons