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.
LAST NEXT MAGMA LAVA Melted rock Melted rock that is beneath that is at or the surface of near the surface the Earth. of the Earth.
LAST NEXT Lava Magma
LAST NEXT LAST NEXT LAST NEXT TYPES OF IGNEOUS ROCKS
Igneous rocks are classified according to where they cooled and solidified.
LAST NEXT INTRUSIVE EXTRUSIVE IGNEOUS ROCKS IGNEOUS ROCKS Rocks that form Rocks that form from magma from lava cooling and cooling and solidifying while solidifying while still inside the at or near the Earth Earth
LAST 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 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 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) P. 6 of ESRT 0% 0%
LAST 6 Physical Setting/Earth Science Reference TablesNEXT — 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.
LAST NEXT INTRUSIVE IGNEOUS ROCKS
PEGMATITE GRANITE *Notice the large mineral crystals
LAST 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 INTRUSIVE IGNEOUS ROCKS 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 DENSITY Range of crystal sizesHIGHER (where the rock formed) FELSIC COMPOSITION MAFIC (rich in Si, Al) (richTexture in Fe, Mg) (description of crystal 100% Names of common 100% Potassium sizes) CHARACTERISTICS intrusive igneous rocks feldspar (pink to white) Non-vesicular means these rocks do 75% 75% Quartz not have any trapped air bubbles (clear to white) Plagioclase feldspar (white to gray) 50% 50% P. 6 of ESRT Pyroxene (green) Biotite LAST (black) NEXT (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.
LAST NEXT EXTRUSIVE IGNEOUS ROCKS
BASALT RHYOLITE *Notice the mineral crystals are so small, you can barely see them
LAST 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.” LAST 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 EXTRUSIVE IGNEOUSoccur due toROCKS 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
Environment of Formation Very ENVIRONMENT OF FORMATION ENVIRONMENT (Plutonic)
Pegmatite Range of crystal sizes or (whereINTRUSIVE the rock formed) coarse larger 10 mm Texture Names of common (description of crystal LIGHTER intrusive igneous rocks COLOR DARKERsizes) 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 P. 6 of ESRT feldspar LAST (pink to white) NEXT 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%
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.
LAST 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) 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)
IGNEOUS ROCK COLORS 0% 0%
LAST 6 Physical Setting/Earth Science ReferenceNEXT 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 (green) Biotite (black) (relative by volume) 25% Olivine 25%
MINERAL COMPOSITION MINERAL (green) Amphibole (black)
0% 0% IGNEOUS ROCK DENSITY
LAST 6 Physical Setting/Earth Science ReferenceNEXT 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 (green) Biotite (black) (relative by volume) 25% Olivine 25%
MINERAL COMPOSITION MINERAL (green) Amphibole (black)
0% 0% IGNEOUS ROCK COMPOSITION
LAST 6 Physical Setting/Earth Science ReferenceNEXT 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 to in particle see density and shape. what minerals may be present in that rock. 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 (green) Biotite (black) (relative by volume) 25% Olivine 25%
MINERAL COMPOSITION MINERAL (green) Amphibole (black)
0% 0% IGNEOUS ROCK MINERALS LAST 6 Physical Setting/Earth Science ReferenceNEXT Tables — 2010 Edition