Earth’s Crust Lab
The earth’s crust is composed of two main rocks, granite and basalt. These rocks are
formed when magma (melted liquid rock) near the earth’s surface that has cooled down
enough to be solid again. The differences between these two rocks are important to
understanding the movements of the earth’s crust.
Problem Question: What are the characteristics of the two main crustal rocks.
Activity 1: Sort the mixture of rocks at your lab table into two piles (A and B). Describe
how you were able to tell them apart.
Rock Group A
Rock Group B
Activity 2: Examine a sample of each rock under the spectroscope. Pay attention to the
different particles or crystals each rock is made of. Sketch a sample of each rock below.
Then describe the colors and sizes of the smaller particles or crystals each rock is made
of.
Rock Group A
Rock Group B
Sketch:
Sketch:
Description:
Description:
Activity 3: Measure the mass of and volume of several pieces of each rock. Calculate
their densities.
Sample 1
Rock A Measurements
Sample 2
Sample 3
Mass (grams)
Volume (mL)
Density (g/mL)
Average Density of rock A = _________________________
Rock B Measurements
Sample 1
Sample 2
Sample 3
Mass (grams)
Volume (mL)
Density (g/mL)
Average Density of rock B = ________________________
Questions:
1) Compare the characteristics of your two rocks. Explain which rock is most likely
to be basalt and which is most likely to be granite.