1. Igneous Rocks Rocks & Minerals Notes: Page 7
©Mark Place,

2. Igneous Rocks
Latin word ignis means fire

3. Igneous Rocks

4. 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

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

6. Volcanoes
Rifts/Ridges

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

8. cooling time

9. crystal size
cooling time

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

11. 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?

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

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

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

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

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

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

20. 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

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

23. 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

24. 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.

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

27. Answers on the Next Page

28. 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