A number of responses occurred over on the MSA-Talk listserv to the discussion about the importance of optical mineralogy since my update yesterday. There was also a great comment added by a fellow-MN resident Bryan Brandli at the end of my previous post I would encourage everyone to read.
Comments that have been posted since Monday at 10.00 CST (its now Tuesday, 10.00) in the pro column:
- Miguel Gregorkiewitz (University of Sienna, Italy): “I’d like to stress that polarized light microscopy is useful to much more than petrography. I started getting involved in materials science as a chemist, and during my PhD, I got eventually stuck for 6 months trying to resolve the crystal structure of a new “hexagonal” phase – until I decided to have a look through the petrographic microscope revealing that my “single” crystal was actually a perfect thrilling of an orthorhombic b=sqrt(3)*a unit cell. At the time, I was happy to find the necessary instruments and knowlegde in our mineralogy department, and now I include the basics of the polarized light microscope and some applications in mineralogy/petrography in my crystallography courses, mainly as a very easy and rapid supporting tool to determine symmetry. I can’t understand why such a simple, cheap and conclusive experimental technique should be sacrificed from our curricula, instead, I would offer it also to solid state physics and engineering labs, to strengthen the training in optics.”
- Volker Gobel (Stephen F. Austin State Univ): “It usually is also an undergraduate deficiency for incoming graduate students. Some U.S. mining industry is bitterly complaining about the unpreparedness of new, young mineralogists lacking basic mineralogic knowledge and microscopic skills necessitating extensive in-house training as academia is failing to do what it once did.”
- Darrell Henry (LSU): “One way in which you can view optical mineralogy (no matter how it is introduced to students) is at a programmatic level or even college/university level. This skill is an excellent way for students to demonstrate critical thinking through hypothesis-testing. After all, when we are doing petrography we are continually generating hypotheses
about the minerals we are observing and then testing these hypotheses using optical properties or, as a short cut, the rock context (what makes sense in that kind of rock). As the experience level of the student rises the sophistication of the hypotheses are elevated as well. At a time, when colleges and universities are asked to demonstrate that
the students are critical thinkers, optical mineralogy can be a vehicle
to do just that.” - Phillippe D’Arco (Universite Pierre et Marie Curie): “In fact fancy techniques have to be applied to decipher some identified problems ! Microprobe does not discriminate sillimanite/andalousite/kyanite, or …. XRD does not tell you anything about phase relation. Texture is a key for rock interpretation. Intensity of Raman lines is highly dependent on orientation, lines can easily disappear.”
- John Hogan (Missouri University of Science and Technology): “One additional unifying skill for geology and geophysics students to develop is understanding the significance of spatial relationships
between critical elements of a problem. I present petrography as geologic mapping of the spatial relationships among minerals at the thin section scale. Being able to identify the minerals is one part of making this map, recognizing the spatial relationships among these minerals is even more important part of making this map, and a lot more difficult to
teach. Tools that identify minerals and mineral compositions, whether you were determining the Fo content of Olivine from the 2V or now using some other weapon of choice (e-probe), these tools will remain a “black box” unless the spatial context of the minerals is utilized to form a testable hypothesis as to how the rock formed.”
I think the following two are more of “this is the way the world currently works” comments:
- Frank Dudas (MIT): “It’s not cutting edge, it’s not “sexy science.” Progress consists of using novel methods and new toys or tools. There is no question that, successively, XRD, the electron microprobe, and other increasingly sophisticated gadgets, most of them black boxes, have offered us the opportunity to gather more precise, accurate, detailed and comprehensive information than a technology that developed in the 19th century, and still depends on that poorest of all observation tools, the human animal. To be “relevant,” we have make sure our students have a 21st century education, and know how to push buttons on black boxes, even though they may not understand how the boxes work. As some poet said, “Progress is a comfortable disease/There’s a hell of a good universe next door/Let’s go.””
- Winton Cornell (Univ of Tulsa): “Now that we’ve been up-and-down the list of reasons/applications/needs of PLM to/in teaching, and in the University environ as a whole (use by non-GEO Departments), I’d like to ask the question re: it’s use by GEO students after they leave academe, this to see/sample what its extension is beyond the classroom these days. That asked, I do already have in hand some info re: – at least – local Independent Oil Companies here in Tulsa/Oklahoma/Texas = where about 1/2 of our students end up working after finishing up GEO here in our mid-continent setting, To quote our Chairman, who has contact with many of these students, and the companies themselves: Winton – “Very little, if any, PLM is done. The larger research labs still do microscopy, but I do not know of any Independents that still do microscopy. Even simple, reflected light microscopy is dying out. And, with the log-while-you-drill technology that’s available, even mud loggers are going away, and as such there is even little well-site geology done these days.” Mind you, he’s not a pessimist, he’s just telling it like it is around here for companies of that scale. We, ourselves, acquired our current CAMECA microprobe from a ‘Major’ that no longer had need for it as a tool. The company did hold on to its light microscopes, though to what end I don’t know. So what is in the ‘sedimentary mineralogy/petrology’ arsenal of oil companies these days? To this info about logging (above), I can add that the ‘hot’ thing around here when it comes to looking into reservoir rocks with microscopy is to do so with dual-beam instruments = SEM-FIB (now that’s a leap!; we have one here and a ‘major’ independent in OK City/at OU has one), with the emphasis on reconstructing/examining pore volume and permeability in shales = the ‘hot’ rocks for natural gas these days. Rendered volumes for SEM-FIB are micrometer-scaled, so for core-scale rendering they use CT scans. Holy cow! Backing all this up is the ‘mineralogy’, it determined via X-ray powder diffraction and modeled via whole pattern fitting (Rietveld). Rocks are thus simple, physical entities evaluated as media that hold oil and gas. Certainly the ‘mining geologists’ touch and examine the rocks? Please say it’s so.”
The last comment occurred yesterday at just after 16.00 CST, so this may be the end of the discussion. If not, I may update again!
Life in Plane Light 
