Making Sense of Igneous Rock Composition- Academic Version

Directions: Use your igneous rocks notes, your igneous rocks lab, and your Bowen’s Reaction

Series chart to fill out the table separating 3 general colors of igneous rocks.

Light Colored Rocks

(white, clear, light

gray, pink)

Intermediate Colored

Rocks

(mix of light and dark

crystals)

Dark Colored Rocks

(dark gray, black,

green)

vocabulary term

for color

elements in

compounds

minerals present

type of crust

plate boundary

viscosity of lava

flow

type of volcanic

eruption

Bowen’s Reaction Series Background Information: Bowen’s Reaction Series explains why certain types of minerals are

usually found together in igneous rocks. As magma cools, certain minerals begin to form at

different temperatures. The continuous series on the right explains the evolution of plagioclase

feldspars from being calcium-rich, to more sodium-rich. The discontinuous series on the left slide

describes the formation of the mafic minerals olivine, pyroxene, amphibole, and biotite mica. As

temperatures begin to cool further, the two branches merge and we begin to see minerals

common to the felsic igneous rocks.

1. Which mineral crystallizes at the highest temperature? What is the percent silica content?

2. Which mineral crystallizes at the lowest temperature? What is the percent silica content?

3. Based on your answers to the previous two questions, how does silica content affect the

temperature at which minerals crystallize in magma?

4. As the magma chamber cools, and the different minerals reach the temperature at which

they crystallize, what happens to the percent silica content of the remaining magma?

5. If a rising magma bubble started out with the compounds that form the mineral Olivine,

why would it have a more Felsic composition as it cooled near the surface?

What

Which mineral crystallizes at the lowest temperature? What is the percent silica content?

Based on your answers to the previous two questions, how does silica content affect the

temperature at which minerals crystallize in magma?

ools, and the different minerals reach the temperature at which

they crystallize, what happens to the percent silica content of the remaining magma?

If a rising magma bubble started out with the compounds that form the mineral Olivine,

why would it have a more Felsic composition as it cooled near the surface?

What’s in a magma Chamber?

Which mineral crystallizes at the lowest temperature? What is the percent silica content?

Based on your answers to the previous two questions, how does silica content affect the

ools, and the different minerals reach the temperature at which

they crystallize, what happens to the percent silica content of the remaining magma?

If a rising magma bubble started out with the compounds that form the mineral Olivine,

why would it have a more Felsic composition as it cooled near the surface?