Download Making Sense of Igneous Rock Composition

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,
ools, 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
What’s in a magma Chamber?