ED13B-0723 INVITED 1340h
Teaching optical mineralogy as a skill for mineral physics
Many people argue that optical mineralogy/petrography is either dead, or a lost art. Consequently, as the undergraduate curriculum in mineralogy and petrology is increasingly compressed into a single course, typically the first component to suffer is optical mineralogy. Here we demonstrate the utility of treating optics within the mineralogy/petrology course as it pertains to preparing the student for graduate and post-graduate research, using mineral physics as a prime example of a burgeoning field in which an understanding of optical mineralogy is required for experimental and theoretical studies. In addition to gaining the obvious skills, such as proper use of the transmitted and reflected light microscope and identification of minerals in thin section, by noting several other important applications of optics in experimental studies, students gain insight into the power and utility of the subject while building an essential bridge to more advanced subjects they may encounter in future coursework and research. Many physical property measurements require the study of oriented single crystals, an often dreaded procedure which can be expedited with a basic understanding of the optical properties of minerals. A familiarity with the optical indicatrix will also aid students in understanding other tensor properties of crystals such as electrical and thermal conductivity (tensors of rank two) and elasticity (a forth-rank tensor). Optical and infrared absorption spectroscopy, Raman spectroscopy, and Brillouin spectroscopy, all widely used techniques in mineral physics, will be easier to grasp for the student with a beginning background in optical mineralogy.
ED13B-0724 1340h
Some not so obvious reasons to teach optical mineralogy
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.
ED13B-0725 1340h
Preparing Students for Petrography and Beyond: A Practical Approach to Optical Mineralogy
Optical Mineralogy at the University of the Pacific is taught as a 1-unit laboratory-based course. In this course students not only learn the techniques for identification of minerals in thin section and get extensive experience studying minerals in thin section. The course meets for one 3-hour lab session each week. In the first half of the semester students learn the techniques of mineral identification: relief, fast/slow directions, interference figures, etc. In the second half of the semester students work independently to compile a notebook of approximately 30 common rock-forming minerals and learn to identify them in thin section. They are provided with numerous thin sections from a wide variety of rocks so that they learn to identify the minerals in context. In the notebook, students compile optical properties and drawings of the minerals in thin section. Students are allowed to use their notebooks on the final exam (identifying minerals in thin section) and thus have additional incentive to generate an excellent product. Students who complete this optical mineralogy lab course are well prepared for the petrographic work they encounter in Petrology the following semester. In addition, they develop confidence in their own investigative and descriptive skills which serves them well in all future work.
ED13B-0726 1340h
Optical Mineralogy at UCLA
Optical mineralogy is taught as part of a required undergraduate course in Earth Materials at UCLA. To strike a balance between teaching a rigorous optical mineralogy course while protecting classroom time for other mineralogy concept instruction, optical mineralogy is presented in two stages. In the first stage, a distillation of optics is presented in lecture, and two laboratories are fully devoted to optical mineralogy. In the second stage, each student will have a personalized project, and will dedicate the last part of their laboratory sessions to learning a single characterization technique at an in-depth level. Options include (but are not limited to): optical mineralogy, X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and electron microprobe. Lecture materials, Laboratories, Summaries of student projects, and student and TA feedback from UCLA's Fall 2004 Earth Materials course will be presented in this session.