HR: 1340h
AN: ED13B-0724    [Abstracts]
TI: Some not so obvious reasons to teach optical mineralogy
AU: * Gunter, M E
EM: mgunter@uidaho.edu
AF: University of Idaho, Geological Sciences, Moscow, ID 83844-3022 United States
AB: Hands-on, interactive, critical thinking, interdisciplinary, spiral learning, and 3-D visualization are familiar words in pedagogy, while Becke lines, dispersion staining, grain mounts, sign of elongation, extinction angle, and optical indicatrix are words seldom used in today's geosciences curriculum. However, the teaching of these seemingly rather historical optical methods, and proper training in the use of the polarized (not petrographic) light microscope (PLM), will by themselves lead to improved learning of our students. And this, if for no other reason, might warrant the inclusion of a semester-long optical mineralogy course. However, another $70 billion per year concern in the U.S. also warrants inclusion of optical mineralogy in a geosciences curriculum. That dollar amount (which would be approximately 10% of annual petroleum sales in the U.S.) centers around the cost spent (wasted?) on asbestos litigation in the U.S. Unfortunately, because we no longer teach PLM skills in the geosciences curriculum, many of the microscopists, regulators, and "expert" witnesses involved in the asbestos issue have little or no formal training in mineralogy or optical mineralogy. This, in turn, often leads to formulation of regulations that make little sense (e.g., that quartz, the most abundant mineral species in the earth's crust is now listed as a human carcinogen) and unsolved mineralogical issues (e.g., OSHA deregulated high-aspect ratio amphibole cleavage fragments in 1994 but did not propose a method to distinguish them from amphibole fibers). The current asbestos issues often deal with tremolite contamination in chrysotile or talc. There are simple PLM methods that we could teach whereby thousands of particles could be screened in minutes to find these possible contaminates, whereas electron beam or X-ray diffraction methods require orders of magnitude more time and cost - and this is only one of many examples. Finally, one might also argue that since minerals comprise rocks which, in turn, comprise the planet it might be wise to teach our students how to identify minerals. Currently, use of the PLM is by far the most efficient and least expensive method to identify minerals, not only in thin section but also in the almost-forgotten oil immersion method. Unfortunately, we have witnessed a decline of the teaching of these methods and use of the PLM mainly because optical mineralogy is viewed as a prerequisite for petrology, and as an emphasis on petrology has declined, giving way to environment-based courses, so too has the need to teach optics. However, optical mineralogy has countless applications, especially in environmental issues relating to dust inhalation, and we, as geosciences educators, can, if we choose, work to meet these societal needs.
DE: 3600 MINERALOGY AND PETROLOGY (replaces
DE: 3625 Descriptive mineralogy
DE: 3694 Instruments and techniques
SC: Education and Human Resourcese [ED]
MN: 2004 AGU Fall Meeting