IGNEOUS ROCKSBEGIN

WHAT IS AN IGNEOUS ROCK?An igneous rock is a rock that has formed from the cooling and solidification

of magma or lava.

NEXT LAST

MAGMAMelted rock

that is beneath the surface of

the Earth.

NEXT LAST

LAVAMelted rock that is at or

near the surface of the Earth.

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MagmaLava

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TYPES OF IGNEOUS ROCKS

Igneous rocks are classified according to where they

cooled and solidified.

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INTRUSIVE IGNEOUS ROCKSRocks that form

from magma cooling and

solidifying while still inside the

Earth

NEXT LAST

EXTRUSIVE IGNEOUS ROCKSRocks that form

from lava cooling and

solidifying while at or near the

Earth

NEXT LAST 6 Physical Setting/Earth Science Reference Tables — 2010 Edition

Ero

s ion

Wea

ther

ing

&E

rosi

on(U

plift

)

Metam

orphism

MeltingSolidific

atio

nMeltingWeathering & Erosion

(Uplift)

Metamorphism

Weathering & Erosion

(Uplift)

Heat and/or Pressure

Heatand /or

Pressure

Melting

Cementation and Burial

Compactio

n and/or Deposition

IGNEOUSROCK

SEDIMENTS

MAGMA

METAMORPHICROCK

SEDIMENTARYROCK

0.0001

0.001

0.01

0.1

1.0

10.0

100.0

PAR

TIC

LE D

IAM

ETE

R (

cm)

Boulders

Cobbles

Pebbles

Sand

Silt

Clay

1000500

50100

10510.5

0.10.05

0.01

STREAM VELOCITY (cm/s)

This generalized graph shows the water velocityneeded to maintain, but not start, movement. Variationsoccur due to differences in particle density and shape.

25.6

6.4

0.2

0.006

0.0004

Rock Cycle in Earth’s Crust

Scheme for Igneous Rock Identification

Relationship of TransportedParticle Size to Water Velocity

Pyroxene(green)

Amphibole(black)

Biotite(black)

Potassiumfeldspar

(pink to white)

(rel

ativ

e by

vol

ume)

MIN

ER

AL

CO

MP

OS

ITIO

N

Quartz(clear towhite)

CH

AR

AC

TER

ISTI

CS

MAFIC(rich in Fe, Mg)

HIGHER

DARKER

FELSIC(rich in Si, Al)

LOWER

LIGHTER

CRYSTALSIZE TEXTURE

Pumice

INT

RU

SIV

E(P

luto

nic)

EX

TR

US

IVE

(Vol

cani

c)

EN

VIR

ON

ME

NT

OF

FOR

MA

TIO

N

Plagioclase feldspar(white to gray)

Olivine(green)

COMPOSITION

DENSITY

COLOR

100%

75%

50%

25%

0%

100%

75%

50%

25%

0%

IGN

EO

US

RO

CK

S

non-

crys

talli

ne

GlassyBasaltic glassObsidian

(usually appears black)

less

than

1 m

m FineBasaltAndesiteRhyolite

1 m

mto

10

mm

CoarsePeri-dotiteGabbro

DioriteGranite

Pegmatite

10 m

mor

larg

er Verycoarse

Scoria Vesicular(gas

pockets)

Dun

ite

Non-vesicular

Non-vesicular

Vesicular basaltVesicular rhyolite Vesicularandesite

Diabase

INTRUSIVE

EXTRUSIVE

P. 6 of ESRT

INTRUSIVE IGNEOUS ROCKSBecause these rocks form inside the

Earth, where it is very hot, it takes a long time for the magma to cool

and solidify. This time allows mineral crystals to grow large. So all intrusive

igneous rocks have inter-grown crystals that are larger than 1mm.

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NEXT LAST

PEGMATITE GRANITE*Notice the large mineral crystals

INTRUSIVE IGNEOUS ROCKS

6 Physical Setting/Earth Science Reference Tables — 2010 Edition

Ero

s ion

Wea

ther

ing

&E

rosi

on(U

plift

)

Metam

orphism

MeltingSolidific

atio

nMeltingWeathering & Erosion

(Uplift)

Metamorphism

Weathering & Erosion

(Uplift)

Heat and/or Pressure

Heatand /or

Pressure

Melting

Cementation and Burial

Compactio

n and/or Deposition

IGNEOUSROCK

SEDIMENTS

MAGMA

METAMORPHICROCK

SEDIMENTARYROCK

0.0001

0.001

0.01

0.1

1.0

10.0

100.0

PAR

TIC

LE D

IAM

ETE

R (

cm)

Boulders

Cobbles

Pebbles

Sand

Silt

Clay

1000500

50100

10510.5

0.10.05

0.01

STREAM VELOCITY (cm/s)

This generalized graph shows the water velocityneeded to maintain, but not start, movement. Variationsoccur due to differences in particle density and shape.

25.6

6.4

0.2

0.006

0.0004

Rock Cycle in Earth’s Crust

Scheme for Igneous Rock Identification

Relationship of TransportedParticle Size to Water Velocity

Pyroxene(green)

Amphibole(black)

Biotite(black)

Potassiumfeldspar

(pink to white)

(rel

ativ

e by

vol

ume)

MIN

ER

AL

CO

MP

OS

ITIO

N

Quartz(clear towhite)

CH

AR

AC

TER

ISTI

CS

MAFIC(rich in Fe, Mg)

HIGHER

DARKER

FELSIC(rich in Si, Al)

LOWER

LIGHTER

CRYSTALSIZE TEXTURE

Pumice

INT

RU

SIV

E(P

luto

nic)

EX

TR

US

IVE

(Vol

cani

c)

EN

VIR

ON

ME

NT

OF

FOR

MA

TIO

N

Plagioclase feldspar(white to gray)

Olivine(green)

COMPOSITION

DENSITY

COLOR

100%

75%

50%

25%

0%

100%

75%

50%

25%

0%

IGN

EO

US

RO

CK

S

non-

crys

talli

ne

GlassyBasaltic glassObsidian

(usually appears black)

less

than

1 m

m FineBasaltAndesiteRhyolite

1 m

mto

10

mm

CoarsePeri-dotiteGabbro

DioriteGranite

Pegmatite

10 m

mor

larg

er Verycoarse

Scoria Vesicular(gas

pockets)

Dun

ite

Non-vesicular

Non-vesicular

Vesicular basaltVesicular rhyolite Vesicularandesite

Diabase

Environment of Formation (where the rock formed)

Names of common intrusive igneous rocks

Range of crystal sizes

Texture (description of crystal

sizes)

Non-vesicular means these rocks do not have any trapped air bubbles

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P. 6 of ESRT

INTRUSIVE IGNEOUS ROCKS

EXTRUSIVE IGNEOUS ROCKSBecause these rocks form on or near the surface of the Earth, where temperatures

are lower, the lava cools and solidifies quickly. Without time,

crystals cannot grow very large, or may not even form at all. So all extrusive

igneous rocks have either no crystals, or crystals that are smaller than 1mm.

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BASALT RHYOLITE*Notice the mineral crystals are so small, you can barely see them

EXTRUSIVE IGNEOUS ROCKS

NEXT LAST

BASALTIC GLASS OBSIDIAN*These extrusive igneous rocks formed so quickly, no crystals were

able to form. They are called “glassy” or “non-crystalline.”

EXTRUSIVE IGNEOUS ROCKS

NEXT LAST

EXTRUSIVE IGNEOUS ROCKS

6 Physical Setting/Earth Science Reference Tables — 2010 Edition

Ero

s ion

Wea

ther

ing

&E

rosi

on(U

plift

)

Metam

orphism

MeltingSolidific

atio

nMeltingWeathering & Erosion

(Uplift)

Metamorphism

Weathering & Erosion

(Uplift)

Heat and/or Pressure

Heatand /or

Pressure

Melting

Cementation and Burial

Compactio

n and/or Deposition

IGNEOUSROCK

SEDIMENTS

MAGMA

METAMORPHICROCK

SEDIMENTARYROCK

0.0001

0.001

0.01

0.1

1.0

10.0

100.0

PAR

TIC

LE D

IAM

ETE

R (

cm)

Boulders

Cobbles

Pebbles

Sand

Silt

Clay

1000500

50100

10510.5

0.10.05

0.01

STREAM VELOCITY (cm/s)

This generalized graph shows the water velocityneeded to maintain, but not start, movement. Variationsoccur due to differences in particle density and shape.

25.6

6.4

0.2

0.006

0.0004

Rock Cycle in Earth’s Crust

Scheme for Igneous Rock Identification

Relationship of TransportedParticle Size to Water Velocity

Pyroxene(green)

Amphibole(black)

Biotite(black)

Potassiumfeldspar

(pink to white)

(rel

ativ

e by

vol

ume)

MIN

ER

AL

CO

MP

OS

ITIO

N

Quartz(clear towhite)

CH

AR

AC

TER

ISTI

CS

MAFIC(rich in Fe, Mg)

HIGHER

DARKER

FELSIC(rich in Si, Al)

LOWER

LIGHTER

CRYSTALSIZE TEXTURE

Pumice

INT

RU

SIV

E(P

luto

nic)

EX

TR

US

IVE

(Vol

cani

c)

EN

VIR

ON

ME

NT

OF

FOR

MA

TIO

N

Plagioclase feldspar(white to gray)

Olivine(green)

COMPOSITION

DENSITY

COLOR

100%

75%

50%

25%

0%

100%

75%

50%

25%

0%

IGN

EO

US

RO

CK

S

non-

crys

talli

ne

GlassyBasaltic glassObsidian

(usually appears black)

less

than

1 m

m FineBasaltAndesiteRhyolite

1 m

mto

10

mm

CoarsePeri-dotiteGabbro

DioriteGranite

Pegmatite

10 m

mor

larg

er Verycoarse

Scoria Vesicular(gas

pockets)

Dun

ite

Non-vesicular

Non-vesicular

Vesicular basaltVesicular rhyolite Vesicularandesite

Diabase

Environment of Formation (where the rock formed)

Names of common intrusive igneous rocks

Range of crystal sizes

Texture (description of crystal

sizes)

Some of these rocks have trapped gas bubbles, some do notP. 6 of ESRT

A quick review...✓ Igneous rocks form from cooled and solidified magma

or lava.

✓ When magma cools slowly inside Earth, we get intrusive (plutonic) igneous rocks with large crystals.

✓ When lava cools quickly at or near Earth’s surface, we get extrusive (volcanic) igneous rocks with small or no crystals. These may be vesicular, meaning there are trapped gas bubbles.

✓ Page 6 of the ESRT shows common igneous rocks and their characteristics.

NEXT LAST

IGNEO

US RO

CK CO

LORS

NEXT LAST 6 Physical Setting/Earth Science Reference Tables — 2010 Edition

Ero

s ion

Wea

ther

ing

&E

rosi

on(U

plift

)

Metam

orphism

MeltingSolidific

atio

nMeltingWeathering & Erosion

(Uplift)

Metamorphism

Weathering & Erosion

(Uplift)

Heat and/or Pressure

Heatand /or

Pressure

Melting

Cementation and Burial

Compactio

n and/or Deposition

IGNEOUSROCK

SEDIMENTS

MAGMA

METAMORPHICROCK

SEDIMENTARYROCK

0.0001

0.001

0.01

0.1

1.0

10.0

100.0

PAR

TIC

LE D

IAM

ETE

R (

cm)

Boulders

Cobbles

Pebbles

Sand

Silt

Clay

1000500

50100

10510.5

0.10.05

0.01

STREAM VELOCITY (cm/s)

This generalized graph shows the water velocityneeded to maintain, but not start, movement. Variationsoccur due to differences in particle density and shape.

25.6

6.4

0.2

0.006

0.0004

Rock Cycle in Earth’s Crust

Scheme for Igneous Rock Identification

Relationship of TransportedParticle Size to Water Velocity

Pyroxene(green)

Amphibole(black)

Biotite(black)

Potassiumfeldspar

(pink to white)

(rel

ativ

e by

vol

ume)

MIN

ER

AL

CO

MP

OS

ITIO

N

Quartz(clear towhite)

CH

AR

AC

TER

ISTI

CS

MAFIC(rich in Fe, Mg)

HIGHER

DARKER

FELSIC(rich in Si, Al)

LOWER

LIGHTER

CRYSTALSIZE TEXTURE

Pumice

INT

RU

SIV

E(P

luto

nic)

EX

TR

US

IVE

(Vol

cani

c)

EN

VIR

ON

ME

NT

OF

FOR

MA

TIO

N

Plagioclase feldspar(white to gray)

Olivine(green)

COMPOSITION

DENSITY

COLOR

100%

75%

50%

25%

0%

100%

75%

50%

25%

0%

IGN

EO

US

RO

CK

S

non-

crys

talli

ne

GlassyBasaltic glassObsidian

(usually appears black)

less

than

1 m

m FineBasaltAndesiteRhyolite

1 m

mto

10

mm

CoarsePeri-dotiteGabbro

DioriteGranite

Pegmatite

10 m

mor

larg

er Verycoarse

Scoria Vesicular(gas

pockets)

Dun

ite

Non-vesicular

Non-vesicular

Vesicular basaltVesicular rhyolite Vesicularandesite

Diabase

IGNEO

US RO

CK DE

NSITY

NEXT LAST 6 Physical Setting/Earth Science Reference Tables — 2010 Edition

Ero

s ion

Wea

ther

ing

&E

rosi

on(U

plift

)

Metam

orphism

MeltingSolidific

atio

nMeltingWeathering & Erosion

(Uplift)

Metamorphism

Weathering & Erosion

(Uplift)

Heat and/or Pressure

Heatand /or

Pressure

Melting

Cementation and Burial

Compactio

n and/or Deposition

IGNEOUSROCK

SEDIMENTS

MAGMA

METAMORPHICROCK

SEDIMENTARYROCK

0.0001

0.001

0.01

0.1

1.0

10.0

100.0

PAR

TIC

LE D

IAM

ETE

R (

cm)

Boulders

Cobbles

Pebbles

Sand

Silt

Clay

1000500

50100

10510.5

0.10.05

0.01

STREAM VELOCITY (cm/s)

This generalized graph shows the water velocityneeded to maintain, but not start, movement. Variationsoccur due to differences in particle density and shape.

25.6

6.4

0.2

0.006

0.0004

Rock Cycle in Earth’s Crust

Scheme for Igneous Rock Identification

Relationship of TransportedParticle Size to Water Velocity

Pyroxene(green)

Amphibole(black)

Biotite(black)

Potassiumfeldspar

(pink to white)

(rel

ativ

e by

vol

ume)

MIN

ER

AL

CO

MP

OS

ITIO

N

Quartz(clear towhite)

CH

AR

AC

TER

ISTI

CS

MAFIC(rich in Fe, Mg)

HIGHER

DARKER

FELSIC(rich in Si, Al)

LOWER

LIGHTER

CRYSTALSIZE TEXTURE

Pumice

INT

RU

SIV

E(P

luto

nic)

EX

TR

US

IVE

(Vol

cani

c)

EN

VIR

ON

ME

NT

OF

FOR

MA

TIO

N

Plagioclase feldspar(white to gray)

Olivine(green)

COMPOSITION

DENSITY

COLOR

100%

75%

50%

25%

0%

100%

75%

50%

25%

0%

IGN

EO

US

RO

CK

S

non-

crys

talli

ne

GlassyBasaltic glassObsidian

(usually appears black)

less

than

1 m

m FineBasaltAndesiteRhyolite

1 m

mto

10

mm

CoarsePeri-dotiteGabbro

DioriteGranite

Pegmatite

10 m

mor

larg

er Verycoarse

Scoria Vesicular(gas

pockets)

Dun

ite

Non-vesicular

Non-vesicular

Vesicular basaltVesicular rhyolite Vesicularandesite

Diabase

IGNEO

US RO

CK CO

MPOS

ITION

NEXT LAST 6 Physical Setting/Earth Science Reference Tables — 2010 Edition

Ero

s ion

Wea

ther

ing

&E

rosi

on(U

plift

)

Metam

orphism

MeltingSolidific

atio

nMeltingWeathering & Erosion

(Uplift)

Metamorphism

Weathering & Erosion

(Uplift)

Heat and/or Pressure

Heatand /or

Pressure

Melting

Cementation and Burial

Compactio

n and/or Deposition

IGNEOUSROCK

SEDIMENTS

MAGMA

METAMORPHICROCK

SEDIMENTARYROCK

0.0001

0.001

0.01

0.1

1.0

10.0

100.0

PAR

TIC

LE D

IAM

ETE

R (

cm)

Boulders

Cobbles

Pebbles

Sand

Silt

Clay

1000500

50100

10510.5

0.10.05

0.01

STREAM VELOCITY (cm/s)

This generalized graph shows the water velocityneeded to maintain, but not start, movement. Variationsoccur due to differences in particle density and shape.

25.6

6.4

0.2

0.006

0.0004

Rock Cycle in Earth’s Crust

Scheme for Igneous Rock Identification

Relationship of TransportedParticle Size to Water Velocity

Pyroxene(green)

Amphibole(black)

Biotite(black)

Potassiumfeldspar

(pink to white)

(rel

ativ

e by

vol

ume)

MIN

ER

AL

CO

MP

OS

ITIO

N

Quartz(clear towhite)

CH

AR

AC

TER

ISTI

CS

MAFIC(rich in Fe, Mg)

HIGHER

DARKER

FELSIC(rich in Si, Al)

LOWER

LIGHTER

CRYSTALSIZE TEXTURE

Pumice

INT

RU

SIV

E(P

luto

nic)

EX

TR

US

IVE

(Vol

cani

c)

EN

VIR

ON

ME

NT

OF

FOR

MA

TIO

N

Plagioclase feldspar(white to gray)

Olivine(green)

COMPOSITION

DENSITY

COLOR

100%

75%

50%

25%

0%

100%

75%

50%

25%

0%

IGN

EO

US

RO

CK

S

non-

crys

talli

ne

GlassyBasaltic glassObsidian

(usually appears black)

less

than

1 m

m FineBasaltAndesiteRhyolite

1 m

mto

10

mm

CoarsePeri-dotiteGabbro

DioriteGranite

Pegmatite

10 m

mor

larg

er Verycoarse

Scoria Vesicular(gas

pockets)

Dun

ite

Non-vesicular

Non-vesicular

Vesicular basaltVesicular rhyolite Vesicularandesite

Diabase

NEXT LAST 6 Physical Setting/Earth Science Reference Tables — 2010 Edition

Ero

s ion

Wea

ther

ing

&E

rosi

on(U

plift

)

Metam

orphism

MeltingSolidific

atio

nMeltingWeathering & Erosion

(Uplift)

Metamorphism

Weathering & Erosion

(Uplift)

Heat and/or Pressure

Heatand /or

Pressure

Melting

Cementation and Burial

Compactio

n and/or Deposition

IGNEOUSROCK

SEDIMENTS

MAGMA

METAMORPHICROCK

SEDIMENTARYROCK

0.0001

0.001

0.01

0.1

1.0

10.0

100.0

PAR

TIC

LE D

IAM

ETE

R (

cm)

Boulders

Cobbles

Pebbles

Sand

Silt

Clay

1000500

50100

10510.5

0.10.05

0.01

STREAM VELOCITY (cm/s)

This generalized graph shows the water velocityneeded to maintain, but not start, movement. Variationsoccur due to differences in particle density and shape.

25.6

6.4

0.2

0.006

0.0004

Rock Cycle in Earth’s Crust

Scheme for Igneous Rock Identification

Relationship of TransportedParticle Size to Water Velocity

Pyroxene(green)

Amphibole(black)

Biotite(black)

Potassiumfeldspar

(pink to white)

(rel

ativ

e by

vol

ume)

MIN

ER

AL

CO

MP

OS

ITIO

N

Quartz(clear towhite)

CH

AR

AC

TER

ISTI

CS

MAFIC(rich in Fe, Mg)

HIGHER

DARKER

FELSIC(rich in Si, Al)

LOWER

LIGHTER

CRYSTALSIZE TEXTURE

Pumice

INT

RU

SIV

E(P

luto

nic)

EX

TR

US

IVE

(Vol

cani

c)

EN

VIR

ON

ME

NT

OF

FOR

MA

TIO

N

Plagioclase feldspar(white to gray)

Olivine(green)

COMPOSITION

DENSITY

COLOR

100%

75%

50%

25%

0%

100%

75%

50%

25%

0%

IGN

EO

US

RO

CK

S

non-

crys

talli

ne

GlassyBasaltic glassObsidian

(usually appears black)

less

than

1 m

m FineBasaltAndesiteRhyolite

1 m

mto

10

mm

CoarsePeri-dotiteGabbro

DioriteGranite

Pegmatite

10 m

mor

larg

er Verycoarse

Scoria Vesicular(gas

pockets)

Dun

ite

Non-vesicular

Non-vesicular

Vesicular basaltVesicular rhyolite Vesicularandesite

Diabase

IGNEO

US RO

CK M

INERA

LS Find the rock name and look below it to see what minerals may be present in that rock.