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** DO NOT Write on this Sheet! **
“Rock Identification Lab”
Introduction:
Rocks are naturally occurring solids that are made of minerals. Rocks can be identified by texture and
composition.
Recall that texture is how a rock feels due to its shape, size, and composition (what it’s made of). Different types
of rocks have different textures due to variation in their crystal size and arrangement (how they are “put
together!”)
Purpose:
In this lab, you will use what you have learned about rocks as well as the information on minerals from Chapter
2 to identify some common rocks.
Problem: How can you use composition and texture to identify common rocks?
Pre-Lab: (complete sentences!)
1. In your own words, describe what is meant by a rock’s “texture.”___________________
__________________________________________________________________
2. What are two types of Igneous Rocks? What distinguishes these two types of Igneous
Rocks? (How are they different?)_________________________________________
__________________________________________________________________
3. What are the three types of Sedimentary rocks? Which type of sedimentary rock would
be formed if we evaporated water that had reactive minerals mixed in it? ___________
__________________________________________________________________
4. Chalk is made of tiny fragments of marine animals. To which group of rocks does chalk
belong? ____________________________________________________________
5. Suppose you observe a rock with very clear bands (stripes). What type of rock might this
be? What other group might it belong to? Explain._____________________________
__________________________________________________________________
Materials:




Rock samples
Hand lens
Pocket knife
Dilute hydrochloric acid
 Colored pencils
 Resources 16 and 17 in the
DataBank
Procedure:
1. Observe one rock sample. Examine its
with and without the hand lens.
1.)
texture, 2.)color,
3.)
crystal size, and
4.)
composition
2.
3.
4.
5.
6.
7.
8.
** DO NOT Write on this Sheet! **
Use Data Table 1 (“Key to Rock Classification”) to classify the sample. Start by reading the
first question, answer YES or NO based on your observations.
After the words “YES” or “NO” you will find directions to proceed to another question, or
you will discover which group your rock belongs to.
If you get to question 8, ask Mr. Jackson for help. We will not be using Hydrochloric
Acid in this lab.
Copy Data Table 2, and record the “route” you take through the key, using the numbers of
the questions. For example, your route might be “1-4-5-Extrusive Igneous Rock.”
Write the name of each rock group in the last column of Table 2 for each sample.
Continue working through the table until you have classified all of your rock samples.
Compare your classifications with those provided by your teacher, when everyone is done.
Correct any mistakes.
Observations
DATA TABLE 1:
(USE this table, do NOT copy it!!)
** DO NOT Write on this Sheet! **
Data Table 2:
COPY & Fill-out this Table!
Letter of Sample
Route Taken
Group to Which Rock
Belongs
Analysis and Conclusion
1. Using Tables & Graphs: How difficult was it to us the key to classify your rock samples?
What problems did you have? ____________________________________________
__________________________________________________________________
2. Generalizations: How useful was the rock’s color in classifying the samples? Explain your
answer.___________________________________________________
__________________________________________________________________
3. Generalizations: Describe the overall texture of each of the MAJOR GROUPS of rocks.
Copy & Complete the following table…
Rock Type
Igneous
Major Rock Group
Description of Texture
Intrusive
Extrusive
Clastic
Sedimentary
Chemical
Biochemical
Metamorphic
-- -- -- n/a -- -- --
Foliated
Nonfoliated
4. Classifying: Which two of the rock samples were the easiest to classify? What
properties made them easy to classify?_____________________________________
__________________________________________________________________