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Partner ________________________
Lab Day: A
Mr. Williams
B
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D
UNIT 2: IGNEOUS ROCK IDENTIFICATION LAB
INTRODUCTION: The type of igneous rock formed when molten magma solidifies
depends on the mineral composition and the rate at which the magma cools.
Igneous rocks that solidify deep underground are called intrusive or plutonic.
They can be observed at the surface when erosion wears away overlying layers.
When magma reaches (or approaches) the surface (lava) it cools to form volcanic
or extrusive igneous rocks. The texture of these extrusive rocks will vary greatly from
ones crystallized from the same magma deep below the surface.
OBJECTIVE: You will investigate the properties by which igneous rocks are identified.
VOCABULARY: Please define on loose-leaf in complete sentences, OR, use in writing
and underline.
LEARN THESE FIRST!!
Igneous
Mafic
Intrusive
Lava
Extrusive
Magma
Felsic
Texture
Porphyrytic
PROCEDURE:
1. Obtain a rock sample.
2. Observe the sample and complete the REPORT SHEET. Use your ESRT, text,
and the FLEXCAM 2000 to help you.
PUT THE ROCK BACK WHERE YOU FOUND IT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
3. Repeat
4. Answer the DISCUSSION QUESTIONS in complete sentences.
DISCUSSION QUESTIONS:
1. Graph the relationship between the size of mineral grains and the rate at which
the magma/lava cools. Also, explain the relationship in a sentence.
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2. How can you determine if an igneous rock has had an intrusive or extrusive
origin? Please be specific.
Example of an unspecific answer: “It depends on the texture.”
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3.
In general, how does the mineral composition of a light colored igneous rock
differ from that of a dark colored igneous rock? Be specific, and give
example(s).
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4. In general, how does the density of a light colored igneous rock differ from that
of a dark colored igneous rock? Be specific and give example(s).
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5. What is the main difference between magma and lava?
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6. Describe the appearance and cause of porphyrytic texture, and name the
porphyrytic rock in the ESRT.
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CONCLUSION:
On what bases are igneous rocks classified?
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Bonus:
Describe the geologic origin (timeframe), associated crustal activity, and general
composition of the “Palisades Sill”.
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