Module 2: Using the Petrographic Microscope
Elizabeth A. Johnson; Juhong Christie Liu; and Mark Peale
Why Learn About Microscopes?
A petrographic microscope is a type of optical microscope used to identify rocks and minerals in thin section and to investigate microscopic textures and features that are present in minerals and rocks. Modern petrographic microscopes use polarized light to help identify minerals using a number of optical techniques.
Microscopes are technology that developed in the mid-1800’s (Sorby, 1882). Yet we still use them today!
Learning Outcomes for the Module
Students will be able to:
- Describe the parts of a thin section and how thin sections are made.
- Operate and describe the parts of a petrographic microscope.
- Troubleshoot issues with using a petrographic microscope.
- Make observations in plane polarized light and crossed polarized light.
- Obtain and identify optical interference figures.
- Use the correct terminology to describe parts of the microscope, measurement techniques, and textures.
- Compile and use distinguishing features of similar minerals to correctly identify them in thin section.
What is NOT Covered in This Module
This module is intended as an introduction to applied optical microscopy for a petrology course, so it does not include ALL possible ways of using a petrographic microscope to analyze minerals and rocks.
If you are interested in learning more in-depth techniques, that is great! The references below provide more detailed discussions of optical techniques and cover additional techniques and microscope accessories, such as the universal stage.
McNamee, B.D. and Gunter, M.E. (2014) Mineralogy and Optical Mineralogy. Lab Manual. 51 pp. Free to download: http://www.minsocam.org/msa/openaccess_publications/
Nesse, W. (2012) Introduction to Optical Mineralogy, 4th edition. Oxford University Press, 384 pp. ISBN-13: 978-0199846276
Raith, M.M., Raase, P. and Reinhardt, J. (2012) Guide to Thin Section Microscopy, 2nd edition 127 pp. ISBN 978-3-00-037671-9 (English) Free to download: http://www.minsocam.org/msa/openaccess_publications/
Sorby, H. C. (1982). Preparation of transparent sections of rocks and minerals: Northern Microscopist, London, 2, 18, 133-140. [Read this eBook Free on Google Play Books site at: https://play.google.com/books/reader?id=SSEuAQAAIAAJ&hl=en&pg=GBS.PA133.]