Chapter 5 - Igneous Rock

Question 1

mafic dyke

Answer 1

a fracture in the rock that is filled with magma from beneath - different composition than surrounding rock

Question 2

plutonic rock

Answer 2

rock that is formed from great depths within crust or mantle

Question 3

phaneritic

Answer 3

minerals large enough to see with unaided eye

ex. granite

Question 4

aphanitic

Answer 4

minerals too small to see

ex. phyolite

Question 5

glassy

Answer 5

no obvious minerals

ex. obsidian

Question 6

porphyritic

Answer 6

two distinct mineral sizes

ex. porphyritic basalt

Question 7

vesicular

Answer 7

many holes or pits in rock surface caused by the trapping of escaping gas
ex. vesicular basalt

Question 8

pyroclastic

Answer 8

fused, glassy fragments, ash, and blocks of rock from explosive volcanic eruption
ex. tuff

Question 9

lava types

Answer 9

pahoehoe - smooth and ropy

Aa - sharp and jagged

Question 10

phenocrysts

Answer 10

large crystals embedded in porphyritic rocks

Question 11

mafic rocks

Answer 11

rocks that are more dense and contain more iron and magnesium

Question 12

felsic rocks

Answer 12

rocks that are less dense and contain more silica

Question 13

felsic rock examples

Answer 13

extrusive- rhyolite

intrusive- granite

Question 14

intermediate rock examples

Answer 14

extrusive- andesite

intrusive- diorite

Question 15

mafic rock examples

Answer 15

extrusive- basalt

intrusive- gabbro

Question 16

ultramafic rock examples

Answer 16

extrusive- peridotite

intrusive- komatiite

Question 17

Bowen’s reaction series

Answer 17

describes the order and process of magma crystallization

Question 18

dike

Answer 18

magma tube that forms in cracks and crosses through layers of rocks

Question 19

pluton

Answer 19

smaller body of magma

Question 20

batholith

Answer 20

very large body of magma

Question 21

xenoliths

Answer 21

solid pieces that have formed in magma (fragments of country rock)

Question 22

sill

Answer 22

horizontal dike

Question 23

laccolith

Answer 23

a sill that contains high pressure magma and lifts the crust above it

Question 24

discordant intrusions

Answer 24

any magma body that cut across layers of country rock that they intrude

Question 25

veins

Answer 25

mineral deposits within rock fractures that are foreign to surrounding country rock.

Question 26

pegmatites

Answer 26

veins of extremely coarse-grained granite due to slow cooling process. water brings elements to crystallization sites.
important source of rare minerals, gemstones, and industrial metals