ESRT_Igneous_Rock_Identification

Answer the following questions based on your interpretation of the Scheme for Igneous Rocks Identification chart of the Earth Science Reference Tables (page 6) as well as your class notes.

1. I am an igneous rock which consists of potassium feldspar, quartz, plagioclase feldspar,

biotite, and hornblende, all of which occur in crystal grains of at least 1 mm in size. My

name is

a. rhyolite b. pumice c. obsidian d. granite

2. Extrusive igneous rocks are also known as

a. intrusive b. plutonic c. volcanic d. felsic

3. I am a volcanic rock that consists of plagioclase feldspar, quartz, hornblende, and biotite.

My name is

a. diorite b. andesite c. obsidian d. basalt

4. Mafic igneous rocks possess

a. high density and light color b. low density and dark color

c. high density and dark color d. low density and light color

5. Which pairs of minerals cannot coexist in either gabbro or basalt?

a. pyroxene and plagioclase feldspar b. olivine and biotite

c. hornblende and plagioclase feldspar d. olivine and pyroxene

6. Which pairs of minerals cannot coexist in either diorite or andesite?

a. quartz and biotite b. olivine and pyroxene

c. olivine and hornblende d. quartz and pyroxene

7. Which mineral is characteristic and diagnostic of granite and rhyolite?

a. quartz b. biotite c. plagioclase feldspar d. potassium feldspar

8. Felsic igneous rocks consist principally of which minerals?

a. plagioclase feldspar, olivine, and pyroxene

b. plagioclase feldspar, pyroxene, and hornblende

c. plagioclase feldspar, quartz, and potassium feldspar

d. hornblende, biotite, and plagioclase feldspar

9. I am an intrusive igneous rock which consists entirely of olivine and pyroxene. My name is

a. dunite b. diorite c. peridotite d. gabbro

10. I am a coarse-grained igneous rock comprised of the following minerals:

Potassium Feldspar: 55%

Quartz: 25%

Plagioclase Feldspar: 10%

Biotite: 7%

Hornblende: 3%

My name is

a. rhyolite b. diorite c. gabbro d. granite

English geologist Wallace S. Pitcher was one of the leading specialists on the geology and genesis of granites and granitic rocks. His interests in the study of granitic rocks was global in scope, and he is credited in having deepened our understanding of these important rocks immeasurably. American geologist Normal L. Bowen is credited with having developed the first systematic scheme for the classification and evolution of igneous rocks, based principally on principles of chemical equilibrium, known as Bowen's Reaction Series.