1. The Scheme for Igneous Rock Identification

2. A Brief Tour

3. Grain Size
Description
Crystal size

4. Igneous rocks have “Intergrown Crystals”

5. Intergrown

6. Intergrown

7. Intergrown

8. Not Intergrown

9. Where it was formed Outside the volcano: Extrusive
Inside the Earth: Intrusive
Where it was formed

10. Bubbles?
Yes= Vesicular

11. Bubbles?
No=Non-vesicular

12. Color Neither Light nor Dark Very Light NotVery Light Not Very Dark
Darkest
Lightest

13. Medium Density
Density
Very Light
Light
Dense
Very Dense

14. Finding The Minerals Unless you have other information,
work in the middle of the rock’s box.
Identify the rock.

15. This is the amount of Potassium Feldspar in the rock.

16. This is the amount of Quartz in the rock.

17. This is the amount of Plagioclase Feldspar in the rock.

18. Use tick marks on a scrap paper to measure the percentage.
Potassium Feldspar 25%
Quartz 40%

19. Name a light-colored, fine-grained
rock with no bubbles.
Practice

20. Name a coarse-grained, dense rock.

21. Name a very light-colored, glassy,
extrusive rock with bubbles.