Rock Concept Map Igneous Rocks ESRT page 6

1. Igneous rocks form from the cooling and solidification of magma (melted rock)

LIQUID HOT MAGMA 2. Magma is a mixture of liquid rock, crystals, and gas

B. Types of Igneous Rocks 1. The cooling rate of magma differs, causing the

a. intrusive igneous rocks • Forms by the slow cooling of magma underground –

• Because underground cooling is SLOWER: – Rock crystals are LARGER & have

b. Extrusive igneous rocks • Fast cooling of LAVA (magma that has reached earth’s

Lava flows forming extrusive igneous rocks (obsidian)

• Because the lava Cools QUICKLY (exposed to colder air), rock crystals are

Rate of Cooling Activity- DO NOT WRITE • When I say “Go” try to

Pumice is an Extrusive Igneous Rock that is VESICULAR (has gas pockets). Because pumice

All light in color, low in density, made up of the same minerals, and

Key idea: -The texture of the igneous rock is determined by the size, shape,

types of magma • FELSIC MAGMA – Light colored – Thick (high viscosity) –

the “bells & whistles” for identifying an IGNEOUS rock 1. Obvious crystals in a

Igneous Rock Video • Watch the video and write down 3 notes • https:

Slides: 26

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Rock Concept Map

Igneous Rocks ESRT page 6

1. Igneous rocks form from the cooling and solidification of magma (melted rock)

LIQUID HOT MAGMA 2. Magma is a mixture of liquid rock, crystals, and gas 3. Magma is less dense than surrounding rocks, and will therefore move upward

B. Types of Igneous Rocks 1. The cooling rate of magma differs, causing the crystal size to also differ

a. intrusive igneous rocks • Forms by the slow cooling of magma underground – “IN” –trusive / “IN” the ground – Also known as PLUTONIC

• Because underground cooling is SLOWER: – Rock crystals are LARGER & have a coarse texture

gabbro pegmatite granite

Granite Mineral Composition

b. Extrusive igneous rocks • Fast cooling of LAVA (magma that has reached earth’s surface)

Lava flows forming extrusive igneous rocks (obsidian)

• Because the lava Cools QUICKLY (exposed to colder air), rock crystals are SMALL and rocks have a fine/glassy texture

Rate of Cooling Activity- DO NOT WRITE • When I say “Go” try to find other students in the class who have the same color that you have- PLEASE WALK! • When I say “Stop”, stop exactly where you are and do not move until I say “GO” again • What happened as I gave you a longer amount of time to find each other?

Pumice is an Extrusive Igneous Rock that is VESICULAR (has gas pockets). Because pumice formed so quickly, the rock formed around the pockets of gas, creating “holes” in the rock. This allows the rock to float in water because of its lower density

All light in color, low in density, made up of the same minerals, and felsic in composition…. What’s the difference? COOLING TIME!

Key idea: -The texture of the igneous rock is determined by the size, shape, and arrangement of the mineral crystals NOT if it is smooth or bumpy -Rock texture is by SIGHT/SIZE, not by TOUCH

types of magma • FELSIC MAGMA – Light colored – Thick (high viscosity) – Contains high amounts of silica • Ex. Granite • MAFIC MAGMA – Dark colored – Thin (low viscosity) – Contains high amount of magnesium & iron • Ex. Basalt