Igneous Rocks Rocks & Minerals Notes: Page 7 ©Mark Place, 2009-2010 www.LearnEarthScience.com

Igneous Rocks Latin word ignis means fire

Igneous Rocks

How are igneous rocks formed? Key Concept #1 How are igneous rocks formed? Please go to the "Rock Cycle" on Page 6 of the ESRTS the melting and solidification of magma

Name two places where igneous rocks form Igneous Rocks: Key Concept #2 Name two places where igneous rocks form

Volcanoes Rifts/Ridges

What determines crystal size? Igneous Rocks: Key Concept #3 What determines crystal size?

cooling time

crystal size cooling time

Large Crystals Indicate long cooling time Small Crystals Indicate short cooling time

What’s the difference between extrusive and intrusive igneous rocks? Igneous Rocks: Key Concept #4 What’s the difference between extrusive and intrusive igneous rocks?

Intrusive Extrusive form on or near the surface (small crystals) form below the surface (large crystals)

Igneous Rocks: Key Concept #5 Characteristics used to classify igneous rocks

Key Concept #5 texture glassy } extrusive fine Characteristics used to classify igneous rocks texture glassy } extrusive fine

Key Concept #5 texture coarse } intrusive very coarse Characteristics used to classify igneous rocks texture coarse } intrusive very coarse

Key Concept #5 color dark light Characteristics used to classify igneous rocks color dark light

low high Key Concept #5 density Characteristics used to classify igneous rocks density low high

Key Concept #5 composition mafic contains Fe and Mg felsic contains Al Characteristics used to classify igneous rocks composition mafic contains Fe and Mg felsic contains Al

Key Identifying Features of Igneous Rocks Igneous Rocks: Key Concept #6 Key Identifying Features of Igneous Rocks

the grains have been melted and are now physically connected Glassy Texture usually black in color Interlocked Grains the grains have been melted and are now physically connected

INTERLOCKING CRYSTALS: Crystals growing into each other The rock is made up of interlocking rectangular feldspars and irregular clear quartz, all in shades of dark grey through to white. The crystals showing yellow colors are mica (muscovite) and tourmaline. Field of view 8 mm.

Please Answer the Questions on Page 8 Using Your Earth Science Reference Tables.

Answers on the Next Page

Stop and complete the Igneous Rock Lab The Answers (Page 8): 1. Basaltic Glass 2. Granite 3. Basalt Stop and complete the Igneous Rock Lab