2.4 Procedure: How to make a thin section
The general procedure for creating thin sections has remained nearly the same since the modern version was created nearly 200 years ago. In this module, we review two examples of modern thin section making procedures. If you have read the history of thin section preparation (section 2.3), you should be already familiar with most of the process.
Describe in the correct order the steps necessary to produce a standard thin section.
Prior Knowledge and Skills
2.2 Thin section and thick section anatomy (recommended)
2.3 History of thin section preparation (recommended)
Frosting a slide
Use Hirsch, Dave (2012; Ret. 11/21/2018) How to make a thin section. https://davehirsch.com/other/thinsections/ to answer these questions:
2.4.1 What do you do to a glass slide to “frost” it?
2.4.2 What is a rock chip?
2.4.3 Why do the instructions say to grind one corner off the glass slide?
2.4.4 What should you do to the rock before you cut a slab out of it?
Watch these videos before answering the following questions:
AMiGEO and Spectrum Petrographics (5/19/2017) Thin Sections ft. Spectrum Petrographics: Welcome to Spectrum.
AMiGEO and Spectrum Petrographics (6/15/2017) Thin Sections ft. Spectrum Petrographics: Behind the Scenes.
2.4.5 Are the Spectrum Petrographics facilities what you imagined a thin section company would look like? Did you know that thin sections are commercially made by Spectrum Petrographics and other companies?
2.4.6 Why does Spectrum Petrographics put quartz grains in the rim of each thin section billet?
2.4.7 How does Spectrum Petrographics label the glass slides?
2.4.8 Approximately how thick is the section after it is initially cut in the cutoff saw?
Use AMiGEO and Spectrum Petrographics (9/14/2017) Thin Sections ft. Spectrum Petrographics: Mineral Stains.
to answer this question:
2.4.9 What are the four types of stains, and what for which mineral is each stain used?
Concept Check 2.4.1
Create a flowchart diagram which puts the following thin section making steps in the correct order. In your diagram, include arrows showing the correct order of steps. Also include some loops showing how it might be necessary to go back and re-do one or more steps if something breaks or fails.
Cut off the chip from the slide.
Either add a cover slip, or fine polish for an electron microprobe finish.
Use epoxy to attach the glass slide to the rock chip.
Label the glass slide with the sample name.
Cut the thin section slab.
Mark the area to be cut on the rock.
Cutting the thin section chip.
Grind the rock to the correct thickness.
Grind a corner of the glass slide.
Frost the slide.
Concept Check 2.4.2
What steps are different between the university lab preparation and the commercial preparation (Spectrum Petrographics)?
If you are unsure of your answers to the Concept Checks, then please re-read and re-watch the References below. Taking notes on the readings and videos is a good way for you to summarize and remember the material.
AMiGEO and Spectrum Petrographics (5/19/2017) Thin Sections ft. Spectrum Petrographics: Welcome to Spectrum. https://youtu.be/_cpyazAOC80
AMiGEO and Spectrum Petrographics (6/15/2017) Thin Sections ft. Spectrum Petrographics: Behind the Scenes. https://youtu.be/Kjry4Q-qMe0
AMiGEO and Spectrum Petrographics (9/14/2017) Thin Sections ft. Spectrum Petrographics: Mineral Stains. https://youtu.be/qIGWga1ElKE
Hirsch, Dave (2012; Ret. 11/21/2018) How to make a thin section. https://davehirsch.com/other/thinsections/
Spectrum Petrographics (Ret. 11/21/2018) http://www.petrography.com/
Licenses and Attributions
YouTube videos created by Spectrum Petrographics (Bonnie Hentosh and Michael DePangher), Elizabeth Johnson, Ceanna Adams, and Juhong Christie Liu. All videos are CC-by licensed.
Text written by Elizabeth A. Johnson, James Madison University (JMU)