Now that you are familiar with how to use a petrographic microscope and some of the optical characteristics that can be observed for minerals, it is possible to identify minerals under the polarizing light microscope (or at least to eliminate some possibilities).
This section is intended for use as a reference for students who have completed the earlier sections of this chapter. Sources to locate optical data as well as images of igneous and metamorphic minerals are compiled below in alphabetical order by reference name.
Please note that this is intentionally NOT a comprehensive table of data for each mineral. In the next section of this chapter (2.10) there is a student synthesis assignment in which students compile their own tables and criteria to distinguish commonly-occurring rock-forming minerals.
Student should be able to:
- Compile optical characteristics of common rock-forming minerals.
- Compare and contrast properties of different minerals including features observed in thin section under plane and cross polarized light..
Resources: Optical Properties
John Fathfull (ret. 1/12/2020) Identification Tables for Common Minerals in Thin Section. http://funnel.sfsu.edu/courses/geol426/Handouts/mintable.pdf
Smith College Geoscience Students (ret. 1/12/2020) Petrographic Data Files. http://www.science.smith.edu/geosciences/petrology/petrography/mineral_list.html
Webmineral.com (ret. 1/12/2020) A to Z listing of minerals . http://webmineral.com/Alphabetical_Listing.shtml#.XhtMwchKhGM
Resources: Minerals in Thin Section
Atlas of Metamorphic Minerals (ret. 1/12/2020) http://www.earth.ox.ac.uk/~oesis/atlas/metmins/index.html
Hollocher, Kurt (ret. 1/12/2020) Igneous Minerals in Thin Section: https://minerva.union.edu/hollochk/c_petrology/ig_minerals.html
Hollocher, Kurt (ret. 1/12/2020) Metamorphic Minerals in Thin Section: https://minerva.union.edu/hollochk/c_petrology/met_minerals.html
Mazdab, Frank K. (ret. 1/12/2020) thin section scans. https://www.rockptx.com/thin-section-scans/
rockPTX (ret. 1/12/2020) Playlist of mineral videos in thin section (ppl, xpl): https://www.youtube.com/channel/UClRPHZ4xYNB6BCQ3zaIv9Pw/playlists
Siddall, R., 2014, Minerals Menu: a catalogue of minerals & textures in thin section. http://www.ucl.ac.uk/~ucfbrxs/PLM/PLMhome.html
Optical and Crystallographic Axes Diagrams
The diagrams below show the geometric relationships between principle optical axes and crystallographic axes for some common biaxial rock-forming minerals. In these diagrams, OA = optic axis; X, Y, and Z are principal optic axes; a, b, and c are crystallographic axes. Crystal faces are labelled with Miller Indices (e.g. 001, 110, etc.).
Optical and crystallographic axes data for figures are taken from:
Deer, W.A., Howie, R.A., and Zussman, J. (1992) An Introduction to the Rock-Forming Minerals (2nd Edition). Prentice Hall. 712 p.
Nesse, W.D. (1991) Introduction to Optical Mineralogy. Oxford University Press, 335 p.
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