Name: ___________________________
Date: ____________ Class Period: ____
Igneous Rock Lab
Objective:
You will determine the name of unknown igneous rocks based on their physical
characteristics, using your notes and Igneous Rock Reference Table.
Materials:
Unknown igneous rock samples
Igneous Rock Reference Tables
Magnifying Glass
Ruler with millimeter measurements
Directions:
For each unknown igneous rock, identify the key physical characteristics. Using your Igneous
Rock Reference Tables, determine the name of the igneous rock based on the observed
characteristics.
Terms to know for this lab:
Vesicular:
The sample looks like gas pockets cover the rock’s surface (think lava rock)
Non-vesicular: The sample does not look to be covered with gas pockets
Mafic:
Contains iron and magnesium, these samples tend to be dark in color
Felsic:
Contains high concentrations of aluminum. These samples tend to be light in color
Sample A:
Examine your sample to complete the table below for color, grain size, and texture. Then, compare your
analysis to the Igneous Rock Reference Table to answer the additional questions about your
sample and to identify your mystery sample. Good luck!
□Light
Color
Grain Size
Texture
□Non-Crystalline
□ Less than 1mm
□ Glassy
□ Fine
□Vesicular
□Dark
□ 1-10mm
□10mm or larger
□ Coarse
□ Very Course
□Non-Vesicular
1. Using the ruler to estimate, what is the approximate grain size on your sample in millimeters? _____
2. Is your sample an intrusive or extrusive rock? ____________________________________________
3. Where did your rock form (above or below Earth’s surface)? ________________________________
4. What type of igneous rock is your sample? ______________________________________________
5. What minerals are present in your sample? ______________________________________________
Sample B:
Examine your sample to complete the table below for color, grain size, and texture. Then, compare your
analysis to the Igneous Rock Reference Table to answer the additional questions about your
sample and to identify your mystery sample. Good luck!
□Light
Color
Grain Size
Texture
□Non-Crystalline
□ Less than 1mm
□ Glassy
□ Fine
□Dark
□ 1-10mm
□10mm or larger
□ Coarse
□ Very Course
□Non-Vesicular
□Vesicular
6. Using the ruler to estimate, what is the approximate grain size on your sample in millimeters? _____
7. Is your sample an intrusive or extrusive rock? ____________________________________________
8. Where did your rock form (above or below Earth’s surface)? ________________________________
9. What type of igneous rock is your sample? ______________________________________________
What minerals are present in your sample? _________________________________________________
Sample C:
Examine your sample to complete the table below for color, grain size, and texture. Then, compare your
analysis to the Igneous Rock Reference Table to answer the additional questions about your
sample and to identify your mystery sample. Good luck!
□Light
Color
Grain Size
Texture
□Non-Crystalline
□ Less than 1mm
□ Glassy
□ Fine
□Vesicular
□Dark
□ 1-10mm
□10mm or larger
□ Coarse
□ Very Course
□Non-Vesicular
10. Using the ruler to estimate, what is the approximate grain size on your sample in millimeters? _____
11. Is your sample an intrusive or extrusive rock? ____________________________________________
12. Where did your rock form (above or below Earth’s surface)? ________________________________
13. What type of igneous rock is your sample? ______________________________________________
What minerals are present in your sample? _________________________________________________