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Date____________________
Rock Identification
In this lab you will classify and identify igneous, sedimentary and metamorphic
rocks. Igneous rocks are classified based on two observable features: color and texture.
Igneous rocks are categorized as either light-colored (usually felsic) or dark-colored
(usually mafic). Texture is based on the size of the crystals within the rock. Coarsegrained rocks have large crystals while fine-grained has small mineral crystals. A rock
with a glassy texture has no crystals.
Sedimentary rocks are classified into three groups: clastic, chemical and organic.
Sedimentary rocks can be identified using three observable features: observable layering
of sediments, presence of fossils and observable sediments (ie, sand in sandstone). You
will use these characteristics to identify numerous sedimentary rocks in your rock kit.
Metamorphic rocks form from pre-existing rock. These rocks can be placed into
two categories: foliated (banded) or nonfoliated (no banding). Foliation is due to the
intense heat and pressure placed on a rock, causing the minerals to group together to form
bands within the rock. Nonfoliated rocks, such as Quartzite and Marble are nonfoliated.
Objectives
Using your reference tables you will:
1. Identify twelve (12) rocks and classify them as igneous,
sedimentary or metamorphic.
Materials
Rock Kit
Earth Science Reference Tables
Notes
Procedure
1. Using your Earth Science Reference Tables and your notes, identify the 12
rock samples found in your rock kit.
2. Fill in the chart with the appropriate information based on your observations,
reference tables and notes.
Sample
Number
1
2
3
4
5
6
7
8
9
10
11
12
Color
Crystals
Layers
Fossils
Foliation
Rock Name
(light or dark)
(yes / no)
(yes / no)
(yes / no)
(yes / no)
(NOT Type)
Conclusion Questions
1. What minerals would you expect to occur in granite? Can you see them?
2. What minerals would you expect to occur in rhyolite? Explain.
3. What minerals would you expect to occur in basalt? How do you know?
4. Which rock is more dense, basalt or granite?
5. How are the particle that make up the conglomerate different from the
particles in the sandstone or the shale?
6. Look carefully at the largest grains in the conglomerate specimen. Of what
mineral are they composed?
7. What chemical test could be used to identify the limestone sample?
8. Why are fossils rare in conglomerates?
9. Compare the minerals that occur in both the granite and gneiss samples.
10. How is gneiss different in appearance from granite?
11. Mica Schist is the most common kind of schist. In it, the flakes of mica are all
parallel and easily seen. Is there a specimen of Mica Schist in your kit?
12. How is the texture of marble different from the texture of quartzite?
13. What test could you use to distinguish marble from quartzite?
14. What general properties of appearance can be used to determine whether are
rock is igneous, sedimentary or metamorphic?