Igneous Rocks

IGNEOUS ROCKS

BEGIN WHAT IS AN IGNEOUS ROCK? An igneous rock is a rock that has formed from the cooling and solidification of magma or lava.

NEXT MAGMA Melted rock that is beneath the surface of the Earth.

LAVA Melted rock that is at or near the surface of the Earth.

NEXT Lava

Magma

NEXT NEXT NEXT TYPES OF IGNEOUS ROCKS Igneous rocks are classified according to where they cooled and solidified.

NEXT INTRUSIVE Rocks that form from magma cooling and solidifying while still inside the Earth

EXTRUSIVE Rocks that form from lava cooling and solidifying while at or near the Earth’s surface

NEXT Page 6 of the ESRT Scheme for Igneous Rock Identification

NEXT Rock Cycle in Earth’s Crust Relationship of Transported

r Dep Particle Size to Water Velocity d/o osi an an tion 100.0 ion n d Bu ct atio ria Boulders pa nt l m e o em 25.6 C C 10.0 Cobbles

SEDIMENTS 6.4 E

(cm)

SEDIMENTARY n r o o

i 1.0 Pebbles

ROCK s s o

H ( i

We Up o r

e a lift n

th ) E a e

M rin 0.2 t g

& & e E a ro M s

l ion g 0.1

n t

i ) n e n d

i t f r t Pre g r s / d/o sur i a n e l o a at e Sand m e p r H ph h amor ism t P t e U o M a ( r r e 0.01 p e

h s W 0.006 i s n s ) o u ft i m li s r p ro e (U IGNEOUS & E Silt g DIAMETER PARTICLE erin ROCK 0.001 ath We g eltin 0.0004 METAMORPHIC M n o Clay ROCK ti a 0.0001

c 1 100 1000 10

i 0.01 0.05 0.1 0.5 500

f 5 50 di M oli el S ting MAGMA STREAM VELOCITY (cm/s)

This generalized graph shows the water velocity needed to maintain, but not start, movement. Variations occur due to differences in particle density and shape.

CRYSTAL TEXTURE Scheme for Igneous Rock Identification SIZE

Non- Obsidian Basaltic glass (usually appears black) Glassy vesicular non-

Pumice Scoria crystalline Vesicular (gas Vesicular rhyolite Vesicular Vesicular basalt pockets) EXTRUSIVE andesite (Volcanic) Fine EXTRUSIVE Basalt

Rhyolite Andesite 1 mm less than Diabase Peri- Non-

Diorite to Coarse IGNEOUS ROCKS Granite Gabbro dotite vesicular 1 mm Dunite 10 mm INTRUSIVE Very ENVIRONMENT OF FORMATION ENVIRONMENT (Plutonic)

Pegmatite or

INTRUSIVE coarse larger 10 mm

LIGHTER COLOR DARKER

LOWER DENSITY HIGHER FELSIC COMPOSITION MAFIC (rich in Si, Al) (rich in Fe, Mg) 100% 100% Potassium CHARACTERISTICS feldspar (pink to white) 75% 75% Quartz (clear to white) Plagioclase feldspar (white to gray) 50% 50% Pyroxene (green) Biotite (black) (relative by volume) 25% Olivine 25%

MINERAL COMPOSITION MINERAL (green) Amphibole (black)

0% 0% NEXT 6 Physical Setting/Earth Science Reference Tables — 2010 Edition INTRUSIVE IGNEOUS ROCKS Because 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.

NEXT INTRUSIVE IGNEOUS ROCKS

PEGMATITE GRANITE

*Notice the large mineral crystals

NEXT Rock Cycle in Earth’s Crust Relationship of Transported

r Dep Particle Size to Water Velocity d/o osi an an tion 100.0 ion n d Bu ct atio ria Boulders pa nt l m e o em 25.6 C C 10.0 Cobbles

SEDIMENTS 6.4 E

(cm)

SEDIMENTARY n r o o

i 1.0 Pebbles

ROCK s s o

H ( i

We Up o r

e a lift n

th ) E a e

M rin 0.2 t g

& & e E a ro M s

l ion g 0.1 n t

i ) n e n d

i t f r t Pre g r s / d/o sur i a n e l o a at e Sand m e p r H ph h amor ism t P t e U o M a ( r r e 0.01 p e h s W 0.006 i s n s ) o u ft i m li s r p ro e (U IGNEOUS & E Silt g DIAMETER PARTICLE erin ROCK 0.001 ath We g eltin 0.0004 METAMORPHIC M n o Clay ROCK ti a 0.0001

c 1 100 1000 10

i 0.01 0.05 0.1 0.5 500

f 5 50 di M oli el S ting MAGMA STREAM VELOCITY (cm/s)

This generalized graph shows the water velocity needed to maintain, but not start, movement. Variations occur due to differences in particle density and shape.

CRYSTAL TEXTURE Scheme for Igneous Rock Identification SIZE

Non- Obsidian Basaltic glass (usually appears black) Glassy vesicular non-

Pumice Scoria crystalline Vesicular (gas INTRUSIVEVesicular rhyolite Vesicular IGNEOUSVesicular basalt ROCKSpockets) andesite (Volcanic) Fine EXTRUSIVE Basalt

Rhyolite Andesite 1 mm less than Diabase Peri- Non-

Diorite to Coarse IGNEOUS ROCKS Granite Gabbro dotite vesicular 1 mm Dunite 10 mm

Very ENVIRONMENT OF FORMATION ENVIRONMENT (Plutonic)

Pegmatite or

INTRUSIVE coarse larger 10 mm

LIGHTER COLOR DARKER

LOWEREnvironment of Formation (where DENSITY HIGHER the rock formed) FELSIC COMPOSITION MAFIC (rich in Si, Al) (rich in Fe, Mg) 100% 100% Potassium CHARACTERISTICS feldspar (pink to white) 75% 75% Quartz (clear to white) Plagioclase feldspar (white to gray) 50% 50% Pyroxene (green) Biotite NEXT (black) (relative by volume) 25% Olivine 25%

MINERAL COMPOSITION MINERAL (green) Amphibole (black)

0% 0%

6 Physical Setting/Earth Science Reference Tables — 2010 Edition Rock Cycle in Earth’s Crust Relationship of Transported

r Dep Particle Size to Water Velocity d/o osi an an tion 100.0 ion n d Bu ct atio ria Boulders pa nt l m e o em 25.6 C C 10.0 Cobbles

SEDIMENTS 6.4 E

(cm)

SEDIMENTARY n r o o

i 1.0 Pebbles

ROCK s s o

H ( i

We Up o r

e a lift n

th ) E a e

M rin 0.2 t g

& & e E a ro M s

l ion g 0.1 n t

i ) n e n d

c 1 100 1000 10

i 0.01 0.05 0.1 0.5 500

f 5 50 di M oli el S ting MAGMA STREAM VELOCITY (cm/s)

This generalized graph shows the water velocity needed to maintain, but not start, movement. Variations occur due to differences in particle density and shape.

CRYSTAL TEXTURE Scheme for Igneous Rock Identification SIZE

Non- Obsidian Basaltic glass (usually appears black) Glassy vesicular non-

Pumice Scoria crystalline Vesicular (gas INTRUSIVEVesicular rhyolite Vesicular IGNEOUSVesicular basalt ROCKSpockets) andesite (Volcanic) Fine EXTRUSIVE Basalt

Rhyolite Andesite 1 mm less than Diabase Peri- Non-

Diorite to Coarse IGNEOUS ROCKS Granite Gabbro dotite vesicular 1 mm Dunite 10 mm

Very ENVIRONMENT OF FORMATION ENVIRONMENT (Plutonic)

Pegmatite or

INTRUSIVE coarse larger 10 mm

LIGHTER COLOR DARKER

LOWEREnvironment of Formation (where DENSITY HIGHER the rock formed) FELSIC COMPOSITION MAFIC (rich in Si, Al) (rich in Fe, Mg) 100% Names of common 100% Potassium CHARACTERISTICS feldsparintrusive igneous rocks (pink to white) 75% 75% Quartz (clear to white) Plagioclase feldspar (white to gray) 50% 50% Pyroxene (green) Biotite NEXT (black) (relative by volume) 25% Olivine 25%

MINERAL COMPOSITION MINERAL (green) Amphibole (black)

0% 0%

6 Physical Setting/Earth Science Reference Tables — 2010 Edition Rock Cycle in Earth’s Crust Relationship of Transported

r Dep Particle Size to Water Velocity d/o osi an an tion 100.0 ion n d Bu ct atio ria Boulders pa nt l m e o em 25.6 C C 10.0 Cobbles

SEDIMENTS 6.4 E

(cm)

SEDIMENTARY n r o o

i 1.0 Pebbles

ROCK s s o

H ( i

We Up o r

e a lift n

th ) E a e

M rin 0.2 t g

& & e E a ro M s

l ion g 0.1 n t

i ) n e n d

c 1 100 1000 10

i 0.01 0.05 0.1 0.5 500

f 5 50 di M oli el S ting MAGMA STREAM VELOCITY (cm/s)

This generalized graph shows the water velocity needed to maintain, but not start, movement. Variations occur due to differences in particle density and shape.

CRYSTAL TEXTURE Scheme for Igneous Rock Identification SIZE

Non- Obsidian Basaltic glass (usually appears black) Glassy vesicular non-

Pumice Scoria crystalline Vesicular (gas INTRUSIVEVesicular rhyolite Vesicular IGNEOUSVesicular basalt ROCKSpockets) andesite (Volcanic) Fine EXTRUSIVE Basalt

Rhyolite Andesite 1 mm less than Diabase Peri- Non-

Diorite to Coarse IGNEOUS ROCKS Granite Gabbro dotite vesicular 1 mm Dunite 10 mm

Very ENVIRONMENT OF FORMATION ENVIRONMENT (Plutonic)

Pegmatite or

INTRUSIVE coarse larger 10 mm

LIGHTER COLOR DARKER

LOWEREnvironment of Formation (where DENSITY Range of crystal sizesHIGHER the rock formed) FELSIC COMPOSITION MAFIC (rich in Si, Al) (rich in Fe, Mg) 100% Names of common 100% Potassium CHARACTERISTICS feldsparintrusive igneous rocks (pink to white) 75% 75% Quartz (clear to white) Plagioclase feldspar (white to gray) 50% 50% Pyroxene (green) Biotite NEXT (black) (relative by volume) 25% Olivine 25%

MINERAL COMPOSITION MINERAL (green) Amphibole (black)

0% 0%

6 Physical Setting/Earth Science Reference Tables — 2010 Edition Rock Cycle in Earth’s Crust Relationship of Transported

r Dep Particle Size to Water Velocity d/o osi an an tion 100.0 ion n d Bu ct atio ria Boulders pa nt l m e o em 25.6 C C 10.0 Cobbles

SEDIMENTS 6.4 E

(cm)

SEDIMENTARY n r o o

i 1.0 Pebbles

ROCK s s o

H ( i

We Up o r

e a lift n

th ) E a e

M rin 0.2 t g

& & e E a ro M s

l ion g 0.1 n t

i ) n e n d

c 1 100 1000 10

i 0.01 0.05 0.1 0.5 500

f 5 50 di M oli el S ting MAGMA STREAM VELOCITY (cm/s)

This generalized graph shows the water velocity needed to maintain, but not start, movement. Variations occur due to differences in particle density and shape.

CRYSTAL TEXTURE Scheme for Igneous Rock Identification SIZE

Non- Obsidian Basaltic glass (usually appears black) Glassy vesicular non-

Pumice Scoria crystalline Vesicular (gas INTRUSIVEVesicular rhyolite Vesicular IGNEOUSVesicular basalt ROCKSpockets) andesite (Volcanic) Fine EXTRUSIVE Basalt

Rhyolite Andesite 1 mm less than Diabase Peri- Non-

Diorite to Coarse IGNEOUS ROCKS Granite Gabbro dotite vesicular 1 mm Dunite 10 mm

Very ENVIRONMENT OF FORMATION ENVIRONMENT (Plutonic)

Pegmatite or

INTRUSIVE coarse larger 10 mm

LIGHTER COLOR DARKER

LOWEREnvironment of Formation (where DENSITY Range of crystal sizesHIGHER the rock formed) FELSIC COMPOSITION MAFIC (rich in Si, Al) Texture(rich (description in Fe, Mg) of 100% Names of common crystal100% sizes) Potassium CHARACTERISTICS feldsparintrusive igneous rocks (pink to white) 75% 75% Quartz (clear to white) Plagioclase feldspar (white to gray) 50% 50% Pyroxene (green) Biotite NEXT (black) (relative by volume) 25% Olivine 25%

MINERAL COMPOSITION MINERAL (green) Amphibole (black)

0% 0%

6 Physical Setting/Earth Science Reference Tables — 2010 Edition Rock Cycle in Earth’s Crust Relationship of Transported

r Dep Particle Size to Water Velocity d/o osi an an tion 100.0 ion n d Bu ct atio ria Boulders pa nt l m e o em 25.6 C C 10.0 Cobbles

SEDIMENTS 6.4 E

(cm)

SEDIMENTARY n r o o

i 1.0 Pebbles

ROCK s s o

H ( i

We Up o r

e a lift n

th ) E a e

M rin 0.2 t g

& & e E a ro M s

l ion g 0.1 n t

i ) n e n d

c 1 100 1000 10

i 0.01 0.05 0.1 0.5 500

f 5 50 di M oli el S ting MAGMA STREAM VELOCITY (cm/s)

This generalized graph shows the water velocity needed to maintain, but not start, movement. Variations occur due to differences in particle density and shape.

CRYSTAL TEXTURE Scheme for Igneous Rock Identification SIZE

Non- Obsidian Basaltic glass (usually appears black) Glassy vesicular non-

Pumice Scoria crystalline Vesicular (gas INTRUSIVEVesicular rhyolite Vesicular IGNEOUSVesicular basalt ROCKSpockets) andesite (Volcanic) Fine EXTRUSIVE Basalt

Rhyolite Andesite 1 mm less than Diabase Peri- Non-

Diorite to Coarse IGNEOUS ROCKS Granite Gabbro dotite vesicular 1 mm Dunite 10 mm

Very ENVIRONMENT OF FORMATION ENVIRONMENT (Plutonic)

Pegmatite or

INTRUSIVE coarse larger 10 mm

LIGHTER COLOR DARKER

LOWEREnvironment of Formation (where DENSITY Range of crystal sizesHIGHER the rock formed) FELSIC COMPOSITION MAFIC (rich in Si, Al) Texture(rich (description in Fe, Mg) of 100% Names of common crystal100% sizes) Potassium CHARACTERISTICS feldsparintrusive igneous rocks (pink to white) Non-vesicular means these rocks do not 75% 75% Quartz have any trapped air bubbles (clear to white) Plagioclase feldspar (white to gray) 50% 50% Pyroxene (green) Biotite NEXT (black) (relative by volume) 25% Olivine 25%

MINERAL COMPOSITION MINERAL (green) Amphibole (black)

0% 0%

6 Physical Setting/Earth Science Reference Tables — 2010 Edition EXTRUSIVE IGNEOUS ROCKS Because 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.

NEXT EXTRUSIVE IGNEOUS ROCKS

BASALT RHYOLITE

*Notice the mineral crystals are so small, you can barely see them NEXT EXTRUSIVE IGNEOUS ROCKS

BASALTIC GLASS OBSIDIAN *These extrusive igneous rocks formed so quickly, no crystals were able to form. They are called “glassy” or “non-crystalline.” NEXT Rock Cycle in Earth’s Crust Relationship of Transported

r Dep Particle Size to Water Velocity d/o osi an an tion 100.0 ion n d Bu ct atio ria Boulders pa nt l m e o em 25.6 C C 10.0 Cobbles

SEDIMENTS 6.4 E

(cm)

SEDIMENTARY n r o o

i 1.0 Pebbles

ROCK s s o

H ( i

We Up o r

e a lift n

th ) E a e

M rin 0.2 t g

& & e E a ro M s

l ion g 0.1 n t

i ) n e n d

c 1 100 1000 10

i 0.01 0.05 0.1 0.5 500

f 5 50 di M oli el S ting MAGMA STREAM VELOCITY (cm/s)

This generalized graph shows the water velocity needed to maintain, but not start, movement. Variations occur due to differences in particle density and shape.

EXTRUSIVEScheme for Igneous IGNEOUS Rock Identification CRYSTAL ROCKSTEXTURE SIZE

Non- Obsidian Basaltic glass (usually appears black) Glassy vesicular non-

Pumice Scoria crystalline Vesicular (gas Vesicular rhyolite Vesicular Vesicular basalt pockets) andesite (Volcanic) Fine EXTRUSIVE Basalt

Rhyolite Andesite 1 mm less than Diabase Peri- Non-

Diorite to Coarse IGNEOUS ROCKS Granite Gabbro dotite vesicular 1 mm Dunite 10 mm

Environment of Formation (where Very ENVIRONMENT OF FORMATION ENVIRONMENT (Plutonic)

Pegmatite or

INTRUSIVE coarse

the rock formed) larger 10 mm

LIGHTER COLOR DARKER

LOWER DENSITY HIGHER FELSIC COMPOSITION MAFIC (rich in Si, Al) (rich in Fe, Mg) 100% 100% Potassium CHARACTERISTICS feldspar (pink to white) 75% 75% NEXT Quartz (clear to white) Plagioclase feldspar (white to gray) 50% 50% Pyroxene (green) Biotite (black) (relative by volume) 25% Olivine 25%

MINERAL COMPOSITION MINERAL (green) Amphibole (black)

0% 0%

6 Physical Setting/Earth Science Reference Tables — 2010 Edition Rock Cycle in Earth’s Crust Relationship of Transported

r Dep Particle Size to Water Velocity d/o osi an an tion 100.0 ion n d Bu ct atio ria Boulders pa nt l m e o em 25.6 C C 10.0 Cobbles

SEDIMENTS 6.4 E

(cm)

SEDIMENTARY n r o o

i 1.0 Pebbles

ROCK s s o

H ( i

We Up o r

e a lift n

th ) E a e

M rin 0.2 t g

& & e E a ro M s

l ion g 0.1 n t

i ) n e n d

c 1 100 1000 10

i 0.01 0.05 0.1 0.5 500

f 5 50 di M oli el S ting MAGMA STREAM VELOCITY (cm/s)

This generalized graph shows the water velocity needed to maintain, but not start, movement. Variations occur due to differences in particle density and shape.

EXTRUSIVEScheme for Igneous IGNEOUS Rock Identification CRYSTAL ROCKSTEXTURE SIZE

Non- Obsidian Basaltic glass (usually appears black) Glassy vesicular non-

Pumice Scoria crystalline Vesicular (gas Vesicular rhyolite Vesicular Vesicular basalt pockets) andesite (Volcanic) Fine EXTRUSIVE Basalt

Rhyolite Andesite 1 mm less than Diabase Peri- Non-

Diorite to Coarse IGNEOUS ROCKS Granite Gabbro dotite vesicular 1 mm Dunite 10 mm

Environment of Formation (where Very ENVIRONMENT OF FORMATION ENVIRONMENT (Plutonic)

Pegmatite or

INTRUSIVE coarse

the rock formed) larger 10 mm

Names of common LIGHTER intrusive igneous rocks COLOR DARKER LOWER DENSITY HIGHER FELSIC COMPOSITION MAFIC (rich in Si, Al) (rich in Fe, Mg) 100% 100% Potassium CHARACTERISTICS feldspar (pink to white) 75% 75% NEXT Quartz (clear to white) Plagioclase feldspar (white to gray) 50% 50% Pyroxene (green) Biotite (black) (relative by volume) 25% Olivine 25%

MINERAL COMPOSITION MINERAL (green) Amphibole (black)

0% 0%

6 Physical Setting/Earth Science Reference Tables — 2010 Edition Rock Cycle in Earth’s Crust Relationship of Transported

r Dep Particle Size to Water Velocity d/o osi an an tion 100.0 ion n d Bu ct atio ria Boulders pa nt l m e o em 25.6 C C 10.0 Cobbles

SEDIMENTS 6.4 E

(cm)

SEDIMENTARY n r o o

i 1.0 Pebbles

ROCK s s o

H ( i

We Up o r

e a lift n

th ) E a e

M rin 0.2 t g

& & e E a ro M s

l ion g 0.1 n t

i ) n e n d

c 1 100 1000 10

i 0.01 0.05 0.1 0.5 500

f 5 50 di M oli el S ting MAGMA STREAM VELOCITY (cm/s)

This generalized graph shows the water velocity needed to maintain, but not start, movement. Variations occur due to differences in particle density and shape.

EXTRUSIVEScheme for Igneous IGNEOUS Rock Identification CRYSTAL ROCKSTEXTURE SIZE

Non- Obsidian Basaltic glass (usually appears black) Glassy vesicular non-

Pumice Scoria crystalline Vesicular (gas Vesicular rhyolite Vesicular Vesicular basalt pockets) andesite (Volcanic) Fine EXTRUSIVE Basalt

Rhyolite Andesite 1 mm less than Diabase Peri- Non-

Diorite to Coarse IGNEOUS ROCKS Granite Gabbro dotite vesicular 1 mm Dunite 10 mm

Environment of Formation (where Very ENVIRONMENT OF FORMATION ENVIRONMENT (Plutonic) Pegmatite Range of crystal sizes or INTRUSIVE coarse

the rock formed) larger 10 mm

MINERAL COMPOSITION MINERAL (green) Amphibole (black)

0% 0%

6 Physical Setting/Earth Science Reference Tables — 2010 Edition Rock Cycle in Earth’s Crust Relationship of Transported

r Dep Particle Size to Water Velocity d/o osi an an tion 100.0 ion n d Bu ct atio ria Boulders pa nt l m e o em 25.6 C C 10.0 Cobbles

SEDIMENTS 6.4 E

(cm)

SEDIMENTARY n r o o

i 1.0 Pebbles

ROCK s s o

H ( i

We Up o r

e a lift n

th ) E a e

M rin 0.2 t g

& & e E a ro M s

l ion g 0.1 n t

i ) n e n d

c 1 100 1000 10

i 0.01 0.05 0.1 0.5 500

f 5 50 di M oli el S ting MAGMA STREAM VELOCITY (cm/s)

This generalized graph shows the water velocity needed to maintain, but not start, movement. Variations occur due to differences in particle density and shape.

EXTRUSIVEScheme for Igneous IGNEOUS Rock Identification CRYSTAL ROCKSTEXTURE SIZE

Non- Obsidian Basaltic glass (usually appears black) Glassy vesicular non-

Pumice Scoria crystalline Vesicular (gas Vesicular rhyolite Vesicular Vesicular basalt pockets) andesite (Volcanic) Fine EXTRUSIVE Basalt

Rhyolite Andesite 1 mm less than Diabase Peri- Non-

Diorite to Coarse IGNEOUS ROCKS Granite Gabbro dotite vesicular 1 mm Dunite 10 mm

Environment of Formation (where Very ENVIRONMENT OF FORMATION ENVIRONMENT (Plutonic) Pegmatite Range of crystal sizes or INTRUSIVE coarse

the rock formed) larger 10 mm

Texture (description of Names of common crystal sizes) LIGHTER intrusive igneous rocks COLOR DARKER LOWER DENSITY HIGHER FELSIC COMPOSITION MAFIC (rich in Si, Al) (rich in Fe, Mg) 100% 100% Potassium CHARACTERISTICS feldspar (pink to white) 75% 75% NEXT Quartz (clear to white) Plagioclase feldspar (white to gray) 50% 50% Pyroxene (green) Biotite (black) (relative by volume) 25% Olivine 25%

MINERAL COMPOSITION MINERAL (green) Amphibole (black)

0% 0%

6 Physical Setting/Earth Science Reference Tables — 2010 Edition Rock Cycle in Earth’s Crust Relationship of Transported

r Dep Particle Size to Water Velocity d/o osi an an tion 100.0 ion n d Bu ct atio ria Boulders pa nt l m e o em 25.6 C C 10.0 Cobbles

SEDIMENTS 6.4 E

(cm)

SEDIMENTARY n r o o

i 1.0 Pebbles

ROCK s s o

H ( i

We Up o r

e a lift n

th ) E a e

M rin 0.2 t g

& & e E a ro M s

l ion g 0.1 n t

i ) n e n d

c 1 100 1000 10

i 0.01 0.05 0.1 0.5 500

f 5 50 di M oli el S ting MAGMA STREAM VELOCITY (cm/s)

This generalized graph shows the water velocity needed to maintain, but not start, movement. Variations occur due to differences in particle density and shape.

EXTRUSIVEScheme for Igneous IGNEOUS Rock Identification CRYSTAL ROCKSTEXTURE SIZE

Non- Obsidian Basaltic glass (usually appears black) Glassy vesicular non-

Pumice Scoria crystalline Vesicular (gas Vesicular rhyolite Vesicular Vesicular basalt pockets) andesite (Volcanic) Fine EXTRUSIVE Basalt

Rhyolite Andesite 1 mm less than Diabase Peri- Non-

Diorite to Coarse IGNEOUS ROCKS Granite Gabbro dotite vesicular 1 mm Dunite 10 mm

Environment of Formation (where Very ENVIRONMENT OF FORMATION ENVIRONMENT (Plutonic) Pegmatite Range of crystal sizes or INTRUSIVE coarse

the rock formed) larger 10 mm

Texture (description of Names of common crystal sizes) LIGHTER intrusive igneous rocks COLOR DARKER LOWER DENSITY HIGHER FELSIC COMPOSITION Some of theseMAFIC rocks have trapped gas (rich in Si, Al) bubbles,(rich in Fe, some Mg) do not 100% 100% Potassium CHARACTERISTICS feldspar (pink to white) 75% 75% NEXT Quartz (clear to white) Plagioclase feldspar (white to gray) 50% 50% Pyroxene (green) Biotite (black) (relative by volume) 25% Olivine 25%

MINERAL COMPOSITION MINERAL (green) Amphibole (black)

0% 0%

6 Physical Setting/Earth Science Reference Tables — 2010 Edition 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 Let’s Take a Closer Look at the ESRT.

NEXT Rock Cycle in Earth’s Crust Relationship of Transported

r Dep Particle Size to Water Velocity d/o osi an an tion 100.0 ion n d Bu ct atio ria Boulders pa nt l m e o em 25.6 C C 10.0 Cobbles

SEDIMENTS 6.4 E

(cm)

SEDIMENTARY n r o o

i 1.0 Pebbles

ROCK s s o

H ( i

We Up o r

e a lift n

th ) E a e

M rin 0.2 t g

& & e E a ro M s

l ion g 0.1

n t

i ) n e n d

i t f r t Pre g r s / d/o sur i a n e l o a at e Sand m e p r H ph h amor ism t P t e U o M a ( r r e 0.01 p e

h s W 0.006 i s n s ) o u ft i m li s r p ro e (U IGNEOUS & E Silt g DIAMETER PARTICLE erin ROCK 0.001 ath We g eltin 0.0004 METAMORPHIC M n o Clay ROCK ti a 0.0001

c 1 100 1000 10

i 0.01 0.05 0.1 0.5 500

f 5 50 di M oli el S ting MAGMA STREAM VELOCITY (cm/s)

This generalized graph shows the water velocity needed to maintain, but not start, movement. Variations occur due to differences in particle density and shape.

CRYSTAL TEXTURE Scheme for Igneous Rock Identification SIZE

Non- Obsidian Basaltic glass (usually appears black) Glassy vesicular non-

Pumice Scoria crystalline Vesicular (gas Vesicular rhyolite Vesicular Vesicular basalt pockets) andesite (Volcanic) Fine EXTRUSIVE Basalt

Rhyolite Andesite 1 mm less than Diabase Peri- Non-

Diorite to Coarse IGNEOUS ROCKS Granite Gabbro dotite vesicular 1 mm Dunite 10 mm

Very ENVIRONMENT OF FORMATION ENVIRONMENT (Plutonic)

Pegmatite or

INTRUSIVE coarse larger 10 mm

LIGHTER COLOR DARKER

LOWER DENSITY HIGHER FELSIC COMPOSITION MAFIC (rich in Si, Al) (rich in Fe, Mg) 100% 100% Potassium CHARACTERISTICS feldspar (pink to white) COLOR 75% 75% Quartz (clear to white) Plagioclase feldspar (white to gray) 50% 50% Pyroxene (green) Biotite (black) (relative by volume) 25% Olivine 25%

MINERAL COMPOSITION MINERAL (green) Amphibole (black)

0% 0% NEXT 6 Physical Setting/Earth Science Reference Tables — 2010 Edition Rock Cycle in Earth’s Crust Relationship of Transported

r Dep Particle Size to Water Velocity d/o osi an an tion 100.0 ion n d Bu ct atio ria Boulders pa nt l m e o em 25.6 C C 10.0 Cobbles

SEDIMENTS 6.4 E

(cm)

SEDIMENTARY n r o o

i 1.0 Pebbles

ROCK s s o

H ( i

We Up o r

e a lift n

th ) E a e

M rin 0.2 t g

& & e E a ro M s

l ion g 0.1

n t

i ) n e n d

i t f r t Pre g r s / d/o sur i a n e l o a at e Sand m e p r H ph h amor ism t P t e U o M a ( r r e 0.01 p e

h s W 0.006 i s n s ) o u ft i m li s r p ro e (U IGNEOUS & E Silt g DIAMETER PARTICLE erin ROCK 0.001 ath We g eltin 0.0004 METAMORPHIC M n o Clay ROCK ti a 0.0001

c 1 100 1000 10

i 0.01 0.05 0.1 0.5 500

f 5 50 di M oli el S ting MAGMA STREAM VELOCITY (cm/s)

This generalized graph shows the water velocity needed to maintain, but not start, movement. Variations occur due to differences in particle density and shape.

CRYSTAL TEXTURE Scheme for Igneous Rock Identification SIZE

Non- Obsidian Basaltic glass (usually appears black) Glassy vesicular non-

Pumice Scoria crystalline Vesicular (gas Vesicular rhyolite Vesicular Vesicular basalt pockets) andesite (Volcanic) Fine EXTRUSIVE Basalt

Rhyolite Andesite 1 mm less than Diabase Peri- Non-

Diorite to Coarse IGNEOUS ROCKS Granite Gabbro dotite vesicular 1 mm Dunite 10 mm

Very ENVIRONMENT OF FORMATION ENVIRONMENT (Plutonic)

Pegmatite or

INTRUSIVE coarse larger 10 mm

LIGHTER COLOR DARKER

LOWER DENSITY HIGHER FELSIC COMPOSITION MAFIC (rich in Si, Al) (rich in Fe, Mg) 100% 100% Potassium CHARACTERISTICS feldspar (pink to white) 75% 75% DENSITY Quartz (clear to white) Plagioclase feldspar (white to gray) 50% 50% Pyroxene (green) Biotite (black) (relative by volume) 25% Olivine 25%

MINERAL COMPOSITION MINERAL (green) Amphibole (black)

0% 0% NEXT 6 Physical Setting/Earth Science Reference Tables — 2010 Edition Rock Cycle in Earth’s Crust Relationship of Transported

r Dep Particle Size to Water Velocity d/o osi an an tion 100.0 ion n d Bu ct atio ria Boulders pa nt l m e o em 25.6 C C 10.0 Cobbles

SEDIMENTS 6.4 E

(cm)

SEDIMENTARY n r o o

i 1.0 Pebbles

ROCK s s o

H ( i

We Up o r

e a lift n

th ) E a e

M rin 0.2 t g

& & e E a ro M s

l ion g 0.1

n t

i ) n e n d

i t f r t Pre g r s / d/o sur i a n e l o a at e Sand m e p r H ph h amor ism t P t e U o M a ( r r e 0.01 p e

h s W 0.006 i s n s ) o u ft i m li s r p ro e (U IGNEOUS & E Silt g DIAMETER PARTICLE erin ROCK 0.001 ath We g eltin 0.0004 METAMORPHIC M n o Clay ROCK ti a 0.0001

c 1 100 1000 10

i 0.01 0.05 0.1 0.5 500

f 5 50 di M oli el S ting MAGMA STREAM VELOCITY (cm/s)

This generalized graph shows the water velocity needed to maintain, but not start, movement. Variations occur due to differences in particle density and shape.

CRYSTAL TEXTURE Scheme for Igneous Rock Identification SIZE

Non- Obsidian Basaltic glass (usually appears black) Glassy vesicular non-

Pumice Scoria crystalline Vesicular (gas Vesicular rhyolite Vesicular Vesicular basalt pockets) andesite (Volcanic) Fine EXTRUSIVE Basalt

Rhyolite Andesite 1 mm less than Diabase Peri- Non-

Diorite to Coarse IGNEOUS ROCKS Granite Gabbro dotite vesicular 1 mm Dunite 10 mm

Very ENVIRONMENT OF FORMATION ENVIRONMENT (Plutonic)

Pegmatite or

INTRUSIVE coarse larger 10 mm

LIGHTER COLOR DARKER

LOWER DENSITY HIGHER FELSIC COMPOSITION MAFIC (rich in Si, Al) (rich in Fe, Mg) 100% 100% Potassium CHARACTERISTICS feldspar (pink to white) 75% 75% Quartz (clear to white) Plagioclase feldspar (white to gray) 50% 50% Pyroxene COMPOSITION (green) Biotite (black) (relative by volume) 25% Olivine 25%

MINERAL COMPOSITION MINERAL (green) Amphibole (black)

0% 0% NEXT 6 Physical Setting/Earth Science Reference Tables — 2010 Edition Rock Cycle in Earth’s Crust Relationship of Transported

r Dep Particle Size to Water Velocity d/o osi an an tion 100.0 ion n d Bu ct atio ria Boulders pa nt l m e o em 25.6 C C 10.0 Cobbles

SEDIMENTS 6.4 E

(cm)

SEDIMENTARY n r o o

i 1.0 Pebbles

ROCK s s o

H ( i

We Up o r

e a lift n

th ) E a e

M rin 0.2 t g

& & e E a ro M s

l ion g 0.1

n t

i ) n e n d

i t f r t Pre g r s / d/o sur i a n e l o a at e Sand m e p r H ph h amor ism t P t e U o M a ( r r e 0.01 p e

h s W 0.006 i s n s ) o u ft i m li s r p ro e (U IGNEOUS & E Silt g DIAMETER PARTICLE erin ROCK 0.001 ath We g eltin 0.0004 METAMORPHIC M n o Clay ROCK ti a 0.0001

c 1 100 1000 10

i 0.01 0.05 0.1 0.5 500

f 5 50 di M oli el S ting MAGMA STREAM VELOCITY (cm/s)

This generalized graph shows the water velocity needed to maintain, but not start, movement. Variations Find the rock name and look belowoccur due to differences it into particle see density and shape.

what minerals may be present in thatCRYSTAL rock.TEXTURE Scheme for Igneous Rock Identification SIZE

Non- Obsidian Basaltic glass (usually appears black) Glassy vesicular non-

Pumice Scoria crystalline Vesicular (gas Vesicular rhyolite Vesicular Vesicular basalt pockets) andesite (Volcanic) Fine EXTRUSIVE Basalt

Rhyolite Andesite 1 mm less than Diabase Peri- Non-

Diorite to Coarse IGNEOUS ROCKS Granite Gabbro dotite vesicular 1 mm Dunite 10 mm

Very ENVIRONMENT OF FORMATION ENVIRONMENT (Plutonic)

Pegmatite or

INTRUSIVE coarse larger 10 mm

LIGHTER COLOR DARKER

LOWER DENSITY HIGHER FELSIC COMPOSITION MAFIC (rich in Si, Al) (rich in Fe, Mg) 100% 100% Potassium CHARACTERISTICS feldspar (pink to white)

MINERALS 75% 75% Quartz (clear to white) Plagioclase feldspar (white to gray) 50% 50% Pyroxene (green) Biotite (black) (relative by volume) 25% Olivine 25%

MINERAL COMPOSITION MINERAL (green) Amphibole (black)

0% 0% NEXT 6 Physical Setting/Earth Science Reference Tables — 2010 Edition LET’S PRACTICE Identify the following igneous rocks using page 6 of the ESRT. Record your answers in your packet.

BEGIN SAMPLE #1

This rock... •contains quartz • has a very coarse texture NEXT SAMPLE #2

This rock... •is vesicular and glassy • is mafic NEXT SAMPLE #3

This rock... •is composed of only olivine

NEXT SAMPLE #4

This rock... •is fine and non-vesicular • has a medium density NEXT SAMPLE #5

This rock... •is glassy • appears black NEXT SAMPLE #6

This rock... •is felsic • has a coarse texture NEXT SAMPLE #7

This rock... •is fairly dense and coarse • can only be intrusive NEXT SAMPLE #8

This rock... •is volcanic with gas pockets • is felsic and glassy texturedNEXT SAMPLE #9

This rock... •is only extrusive • is mafic, fine, with no holesNEXT SAMPLE #10

This rock... •has a medium color • has a coarse texture NEXT SAMPLE #11

This rock... •is glassy • contains pyroxene NEXT SAMPLE #12

This rock... •contains olivine • contains pyroxene NEXT SAMPLE #13

This rock... •has a medium color

NEXT SAMPLE #14

This rock... •may be volcanic or plutonic

NEXT SAMPLE #15

This rock... •is vesicular, fine • contains Potassium FeldsparNEXT SAMPLE #16

This rock... •has a fine texture • is felsic, non-vesicular NEXT SAMPLE #17

This rock... •has a fine, vesicular texture • is dark in color NEXT You’re Done!

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