Igneous Rocks

Question 1

rocks

Answer 1

aggregates of 1(+) minerals or mineraloids

Question 2

igneous rocks

Answer 2

rocks which formed from melted rock that cooled

Question 3

steps of the rock cycle

Answer 3

weathering
metamorphism
melting
recrystallization

Question 4

weathering

Answer 4

mechanical/chemical processes that break a larger rock into smaller pieces or its chemical components

Question 5

metamorphism

Answer 5

change that occurs in a rock due to extreme amounts of heat and/or pressure (NOT melting)

Question 6

melting

Answer 6

when a rock becomes a liquid due to extreme heat

Question 7

recrystallization

Answer 7

formation of new minerals under conditions of extreme heat or pressure

Question 8

magma

Answer 8

melted rock below earth’s surface

Question 9

lava

Answer 9

melted rock above earth’s surface

Question 10

2 types of igneous rocks

Answer 10

intrusive and extrusive

Question 11

intrusive rocks

Answer 11

form from magma cooling inside the earth; have larger crystals than extrusive rocks because they have more space and time to grow

Question 12

extrusive rocks

Answer 12

form from lava cooling on earth’s surface; have smaller crystals than intrusive rocks since they cool rapidly

Question 13

identifying factors of igneous rocks

Answer 13

texture
mineral composition

Question 14

types of textures

Answer 14

pegmatitic
phaneritic
aphanitic
porphyritic
glassy
vesicular
pyroclastic

Question 15

True or False: Pegmatitic and phaneritic textures are extrusive

Answer 15

False; they’re INTRUSIVE

Question 16

True or False: aphanitic textures are extrusive

Answer 16

True

Question 17

pegmatitic texture

Answer 17

has crystals larger than 30mm [very visible with the naked eye]

Question 18

phaneritic texture

Answer 18

has crystals 1-30 mm in size [visible to the naked eye]

Question 19

aphanitic texture

Answer 19

has crystals smaller than 1mm

Question 20

porphyritic texture

Answer 20

a combo of phaneritic and aphanitic texture

Question 21

glassy texture

Answer 21

created when lava cools so fast the minerals (crystals) can’t form; it is thus a mineraloid

Question 22

vesicular texture

Answer 22

contains many tiny holes resulting from gases escaping from cooling lava

Question 23

pyroclastic texture

Answer 23

contains fragments of broken volcanic rock because of explosive volcanism [a chaotic-looking mixture of vesicular & other rocks]

Question 24

types of igneous mineral composition

Answer 24

felsic (light-coloured [& has lots of silicates])

intermediate (in-between light- and dark- coloured [gray])

mafic (dark-coloured [not as much silicates])

Question 25

dikes

Answer 25

typically-vertical magmatic intrusions/openings in the rock below the surface; tend to flow against the grain of the rock

Question 26

sills

Answer 26

typically-horizontal magmatic intrusions/openings in the rock below the surface; tend to flow with the grain of the rock

Question 27

plutons (& their larger counterparts, batholiths)

Answer 27

large magmatic bodies below the surface

Question 28

xenolith

Answer 28

solid rock around which magma crystallizes

Question 29

Bowen's reaction series

Answer 29

describes the sequence of mineral crystallization from cooling magma, illustrating how different minerals solidify at different temperatures, leading to the formation of various igneous rock types and textures.

Question 30

True or False: Igneous rocks are usually the only rocks that can yield radioactive [not carbon] dates

Answer 30

True