Lab #_____ Igneous Rocks
Objective: Students will become familiar with and identify the characteristics of
Igneous rocks.
Vocabulary: - igneous - felsic - mafic - magma - lava - intrusive - extrusive texture - vesicular - crystalline Procedure:
1. Obtain the bag of sedimentary rock samples from your instructor.
2. Complete the chart using your samples and the Scheme for Igneous Rock
Identification on pg 6 of the Earth Science Reference Tables.
Questions:
1. How is the size of the mineral grains affected by the rate at which the
molten rock material cools?
2. How can you determine that an igneous rock is intrusive or extrusive in
origin?
3. In general, how does the characteristic mineral composition of a light
colored igneous rock differ from that of a dark colored igneous rock?
4. In general, how does the density of a light colored igneous rock differ for
that for a dark colored igneous rock?
5. What is the difference between magma and lava?
6. Which rock samples probably formed deep within the earth? How would
you know?
7. Which rock sample formed most quickly? How would you know?
Conclusion:
Describe in detail how Intrusive Igneous rocks and extrusive igneous rocks
form. Identify distinguishing characteristics.
Color
(light or dark)
Density
(high or low)
Compostion
Minerals Present
Extrusive or
Intrusive
Sample
Texture
(Felsic or Mafic)
Report Sheet
Rock Name
1
2
3
4
5
Rock Sample
Rock Name
Distinguishing
Characteristics