An example mineralogy course - from the field to the Web

Mickey Eugene Gunter

Department of Geology and Geological Engineering

University of Idaho

Moscow, Idaho 83844-3022

e-mail: gunter@uidaho.edu

WWW: http://www.webpages.uidaho.edu/~mgunter/

Abstract

Mineralogy serves a central role in the education of any earth science student, and no doubt minerals are one of the most exciting objects found in nature. Yet, mineralogy is often viewed as a "boring" course because of the large amount of memorization and lack of relevance, among other things. What can we, as professors of mineralogy do to engage students better in a mineralogy course? I have attempted to improve my presentation of mineralogy by using a mix of several teaching methods and activities, while at the same time attempting to keep the course intellectually rigorous.

I have integrated optical mineralogy into the course along with several other analytical methods. The lecture portion of the course is divided into three main sections: crystallography, crystal chemistry, and silicate mineralogy. The lab mostly parallels the lecture but departs slightly mid-semester to cover non-silicate minerals. After a background in crystallography and crystal chemistry has been established, silicate mineralogy is presented, with one simple reoccurring theme: the physical properties of minerals are directly related their crystal structure. Because this is the case, a thorough understanding of the arrangement of atoms at the atomic level allows us to predict the behaviors of minerals in a dynamic geological environmental.

Key words: mineralogy & crystallography, teaching & curriculum, optical mineralogy

Introduction

Mineralogy is the probably the most important course in a geosciences curriculum. While this may seem like a blessing to the mineralogy community, it might be a curse. Mineralogy usually serves as a prerequisite to many other courses and has the reputation as the "weed-out" course. Most non-mineralogists think that mineralogy should function as a means to an end - to teach students to identify minerals, and thus to classify rocks. This is most certainly one of the goals of a mineralogy course, but not the only goal. For instance, since the physical properties of minerals are directly related to the mineral's crystal structure, a thorough understanding of crystal structures will allow the student to predict the physical properties based upon the structure - not just memorize them.

With geoscience departments being forced to trim operating budgets, the mineralogy position (i.e., filled by a traditional mineralogist - whatever that is) may be targeted because several existing faculty in the department may also be able to teach mineralogy (i.e., because mineralogy is so important, many other faculty have some level of expertise in it). These non-mineralogy faculty often teach the course in the "means to an end" method, which results in even more memorization for students (e.g., they just memorize that feldspars have low birefringence without knowing why). Also many faculty do not realize exactly what a mineralogists does, as I experienced when I became an assistant professor. At first faculty and students would routinely bring me thin sections to identify unusual minerals. In graduate school, we studied crystal structures not thin sections, and looked at ball and spoke models of minerals. Petrologists are much better equipped to identify minerals in thin section, but they often lack the theoretical understanding of why minerals look as they do. Many faculty tend to teach mineralogy as a rather boring course because they themselves fail to see the relevance of mineralogy beyond their own fields both inside and outside of the geoscience environment. However, this does not need to be the case, and it is up to the current university mineralogy faculty to inject more enthusiasm and relevance into their mineralogy courses. As Brady (1995) points out, we should attempt to make mineralogy the students' favorite course instead of one of their most dreaded. Brady et al. (1995) and Brady & Boardman (1995) give some relevant new examples of lab exercises that can be performed a mineralogy class.

I have attempted to design a course that departs somewhat from traditional mineralogy courses. The course meets in the spring semester instead of the fall, which gives students, especially transfer students, time to complete the chemistry prerequisite. The course counts as 5 semester credits and has three 50-minute lectures per week (M,W,F) and two 2-hour labs per week (T,Th), along with some weekend field trips and meetings in the instrument labs. The course is an integrated - not combined - course in mineralogy and optical mineralogy. Previously, our department had separate 3-credit courses in mineralogy and optical mineralogy, taught in the fall and spring semester respectively. It may seem strange that I as an optical mineralogist would eliminate the separate class in optical mineralogy, but integrating it with mineralogy into a one-semester course seems to have worked, with little or no loss of relevant content, while reducing the number of credits and courses the students must take. However, it should be emphasized that knowledge of optical mineralogy and ability to use the petrographic microscope are still a requirements in our curriculum and necessary for an undergraduate degree in the geosciences.

This paper is not intended to be an exhaustive description of my mineralogy course but is meant to share some of my ideas and overall course structure. No one mineralogy course would satisfy all faculty and students at all universities and colleges. For those wishing more detail about my course, including all the lecture notes, lab exercises, handouts, quizzes, homework sets, field trips, I am "publishing" my entire course this semester (Spring '96) on the Web, at http://www.webpages.uidaho.edu/~mgunter/. Throughout this paper, I will refer to the Web site as Gunter (1996) and list the address with the references.

General course overview

Probably the most difficult aspect in teaching any course is to determine what material to include (or rather, what material to exclude). This is especially challenging in mineralogy, because, as stated above, most faculty, and students, view mineral identification based upon physical properties as the main, if not sole, goal for a mineralogy course. However, to a mineralogist, it seems important to present the basics of crystallography and crystal chemistry as well as to introduce several analytical methods, both modern and classical, which mineralogists use to characterize and identify minerals. Of all of the analytical methods, the light microscope is still the most efficient tool for the students to use and is thus an essential part of any mineralogy course or curricula. However, as many other analytical methods as possible should be introduced to the students, depending upon the professor's expertise and the equipment at or near the institution.

Before selecting the course content, first ascertain what the students should know about minerals (i.e., set the goals for the course). The goals will differ among faculty members, and certainly no single set of goals exist for everyone. My main goals for the course are:

* introduce crystallography, crystal chemistry, and systematic mineralogy

* relate the physical properties of minerals to their crystal structures

* introduce analytical methods used in modern mineralogy, especially the polarizing light microscope

* learn how minerals are classified

* identify minerals in hand specimen and thin section and with the aid of various analytical techniques

My course content is driven by the above five goals. Also, with over 4,000 known minerals the decision must be made on what groups of minerals to include and exclude, both in lecture and lab. With approximately 92% of the earth's crust by weight composed of silicate minerals, clearly silicate mineralogy should predominate. This is not to underestimate the importance, especially economical, of the non-silicate minerals, but the major rock forming minerals are the silicates, and every geoscience student must have a good background in them. Other courses that follow mineralogy can stress other mineral groups. For instance, an elective course in economical geology would most certainly have a major emphasis on the non-rock forming minerals.

The lecture section of the course is basically divided into three parts: crystallography, crystal chemistry, and silicate mineralogy, with the first two sections providing the background for a thorough, conceptual understanding of silicate minerals. The lab begins with symmetry and then moves to optical crystallography while the lecture is still in the crystallography section. When the lecture moves to crystal chemistry, the lab begins to address non-silicate minerals. By the time these topics are completed, silicate mineralogy begins in both lecture and lab, with lecture stressing the crystal structures and crystal chemistry of the silicates and lab dealing with mineral identification in hand samples, rock samples, and thin sections. At the end of the semester end each student gives a 10-15 minute presentation and writes a summary paper on one of the non-silicate mineral groups, with the main focus of the research relating the physical properties of each group to its crystal structure.

The selection of books for a combined mineralogy / optical mineralogy course can prove difficult to the instructor and expensive to the student. Currently, I use Klein and Hurlbut (1993) for the crystallography, crystal chemistry, and systematic mineralogy portions of the course and Nesse (1991) for the optical mineralogy content. However, with the recent availability of Bloss' classical book on and crystal chemistry (Bloss, 1971) at a very low price from the Mineralogical Society of America, I am tempted to change. Although, this book lack descriptions of minerals in thin sections and hand samples, with the increasing availability of mineralogical computer databases both on the Web (Gunter, 1996) and as stand alone programs, this void could be filled relatively inexpensively by these computer databases.

Detailed course content

Crystallography: During the first lab period, which is also our first class meeting, I give a tour and conduct demonstrations of most of the mineralogy related analytical equipment in our department. This includes the scanning and transmission electron microscopes, powder and single crystal x-ray diffractometers, and my optical microscopy research lab. Many times, especially in research universities, the undergraduates never see "behind the closed doors" and into our research labs. This first day is also a great way for me to meet all of the students in an informal setting.

Lecture and lab are integrated, and at the start of the semester I give several (lengthy) lectures in lab. (Possibly, the methods I use to teach this course would work better if there were no TA; this way, the mix of lecture, lab, demonstrations, and activities might be enriched because one person would be in charge of both lecture and lab and could better integrate the material.) The course starts in the rather traditional manner with point group symmetry and crystal systems. In lab, wooden blocks are spun and stereonets projected. While the wooden blocks may seem too classical, I cannot find a better way to teach symmetry than this hands-on approach. All during this period of the class, I frequently discuss how the physical properties of minerals relate to their symmetry. For instance, most students recall from physical geology that kyanite has two separate observable hardness values. This can be related to its low symmetry. And, it is the lack of a center of symmetry that gives quartz its piezoelectric properties and, in turn, its widespread use as a time keeping device. I also discuss how light can travel at different speeds in low symmetry materials and at the same speed in higher symmetry ones.

Given point symmetry as a basis, optical symmetry is introduced, because optical symmetry is a type of point symmetry. The symmetry of the optical indicatrix is described and then in turn related to the crystal systems (Gunter, 1992). At this point in the lab, the students are working with the petrographic microscope. In the first week they "play with the scopes" and look at thin sections of basalt and granite. These two rocks have been selected for several reasons: they are the most abundant extrusive and intrusive igneous rocks, they contain good examples of the most common rock forming minerals, and both of them outcrop in our area (northern Idaho). At this point, the students are gaining some hands-on experience about how to use the light microscope without yet learning any theory about how light interacts with minerals. All during the course, I try to show mineral samples in hand specimens, rocks, and thin sections.

Next, in lecture I discuss refractive indices and other properties of how light interacts with minerals (e.g., pleochroism, absorption). These phenomena are also shown in lab with a combination of thin sections and grain mounts.

We return to point groups but add the translational component of symmetry to create the space groups. In both point group and space group development, I use both a phenomenological and mathematical approach. The mathematical approach was derived from Boisen and Gibbs (1990). While quite possibly seeming like the most abstract and esoteric aspect of a mineralogy course, crystallography is still the heart (literally) and soul (figuratively), of minerals. The main goal of introducing space groups is to show the students how crystal structures of minerals can be represented given their space group, unit cell parameters, and atomic positions. With this background, the students gain an understanding of how computer programs such as ATOMS (Dowty, 1993) can be used to draw crystal structures or how ball and spoke models can be made with the aid of a computer program called DRILL (Gunter and Downs, 1991), which is available from my Web site (Gunter, 1996). Also, I return to explain some of the theory of how x-ray diffraction can be used to identify minerals and to perform crystal structure work and how energy dispersive methods can be used to determine the chemistry of minerals. This concludes the section of the course on crystallography, hopefully leaving the students with an understanding of how we can represent a mineral's crystal structure.

Crystal Chemistry: The second major topic area in lecture is crystal chemistry. At this point, the lecture and lab diverge. In lab, the students work on identification of non-silicate minerals based upon their physical properties. This portion of the lab is still taught in a somewhat traditional manner - that is, the students look at trays of minerals and try to identify them based upon the old-fashioned, simple tests (hardness, streak, color, etc.). Most of the students are ready to handle some real minerals, so they start enjoying the course a bit more.

It is difficult to decide which minerals to include in lab for both silicates and non-silicates. At a poll in a MSA-NAGT theme session on Mineralogy Teaching (1993 GSA meeting), only one faculty member gave over 100 minerals in lab. Clearly the most abundant silicates must be included, but what else? I favor inclusion of more forms of common minerals at the expense of the rare minerals. For instance, I give the students several different calcite samples instead of less common carbonates. The geological setting will also drive the mineral selection. See Gunter (1996) for a list of minerals used in the various labs.

The crystal chemistry portion of the course stresses the building blocks of minerals - atoms and simple arrangement of ions (e.g., tetrahedrons, octahedrons, and their polymerization). Given the atoms, their ionic charge, and size are introduced. The students must memorize the eight most abundant elements in the crust, their ionic charge, and ionic size (O2-=1.4Å, Si4+=0.4Å, Al3+=0.5Å, Fe2+/3+=0.7Å/0.6Å, Ca2+=1.0Å, Na+=1.0Å, K+=1.3Å, Mg2+=0.7Å). Given this sparse amount of information, the students can use it, much like we use the alphabet and grammar rules to communicate, to understand chemical formulas and crystal structures. The goal in this entire processes is to show that minerals are just arrangements of ions and groups of ions.

I stress two main criteria for mineral's to exist: the elements must fit together (this is why I want them to know the relative size of the ions) and the charges must balance (this is why they must know the ionic charges). Given the approximate size, the theory of coordination polyhedron is developed. The radius ratio rules are not taught as if they are carved in stone, but the point is made that certain elements have certain coordination polyhedral, and thus coordination numbers, based on the sizes and how ions pack. It is stressed that the radius of an atom is based on several factors (e.g., charge, coordination number, spin state).

Given the coordination number (CN) concept, and realizing that O2- is the most abundant element in the earth's crust, and that the CNs are based on oxygen, we arrive at a set of coordination numbers for the next seven most abundant elements (i.e., Si = 4, Al = 4-6, Fe = 6, Ca = 6-8, Na = 6-8, K = 8-12, Mg = 6). Of course, there are exceptions to these values: for instance, Si can have a CN of 6. The significance of this, and of changing coordination numbers, can then be related to pressure; high pressure minerals tending to have higher coordination numbers. This, in turn, shows how the atomic structure of a mineral can be directly used to interpret its formation. I tend to save most of these rules on relating mineral physical properties to crystal structure and interpreting formation conditions until after I give a more complete discussion of silicate mineralogy.

Silicate mineralogy: Because silicate minerals compose 92% of the earth's crust, they are unarguably the single most important mineral group. Approximately 50% of the course, both lab and lecture, is dedicated to this mineral group. As stated above, the other mineral groups are covered in lab and students do a research project on them, so the non-silicates are also covered in the course.

Given the introduction to crystal chemistry and the knowledge that O and Si are the two most abundant elements in the earth's crust and that Si's CN = 4 for O, I ask the students to write a balanced chemical formula with just Si and O. They quickly write SiO2 and remember that this is the formula for quartz. This is my starting point for discussion of the silicate mineral group, thus starting with the silica polymorphs.

For each of the silicate subgroups, I follow a distinct outline: chemistry, crystal structure, physical properties, occurrence, and "fun facts." The entries in the outline are self explanatory, with the exception of "fun facts." I try to find some important, or relevant, example of a mineralogical phenomenon for each group . For instance, I show how CN changes from 4 to 6 with the silica polymorphs. The P-T diagram is shown under occurrences, and the point can be made that SiO2 formed at high pressure and low temperature (meteorite impacts) and has a CN = 6. This, in turn, can be related to many minerals with increased CN at higher pressure (e.g., in Al2SiO5, one Al always has a CN=6, while the other goes from CN=4, 5, 6 when going from low pressure to high pressure, sillimanite, to andalusite, then kyanite, respectively). Also, when addressing each group, the crustal abundance is given (e.g., 12% for quartz). For the silica polymorphs, and most other subgroups, some sort of graphical mineral nomenclature is given (Gunter, 1996). For the silica polymorphs, it is the P-T diagram. Students seem much better equipped to recall the diagram with associated mineral names and formation conditions than just a list of mineral names.

Given the chemical formula for quartz as a starting point, the chemical formulas for the feldspars can be derived as follows: multiply SiO2 by 4, yielding Si4O8, then substitute 1 Al for 1 Si, giving (AlSi3O8)1-. Next, just add K to get KAlSi3O8 or Na to get NaAlSi3O8. Substitute another Al for Si to get (Al2Si2O8)2-, then add Ca. This thus gives the three end-member feldspars. Of course, a triangular diagram is best used to represent these, along with feldspars of intermediate composition.

There are lots of "fun facts" about feldspars. One example I use is the polymorphs of KAlSi3O8 (sanidine, orthoclase, microcline). At this point order/disoder and symmetry reductions are introduced to show how atomic level arrangement of Al/Si in tetrahedrons can be used to determine the petrogenic history of a rock.

After the silica polymorphs and feldspars have been covered, I discuss depolymerization of silicate tetrahedron. In these two groups the tetrahedrons were fully polymerized into framework silicates. (I prefer framework over tectosilicates, and likewise sheet silicates over phyllosilicates, and chain silicates over inosilicates; in general I question every "big" word I use and try to find an intuitive way to say the same thing.)

I stress the ratio of tetrahedral cations for each group of the silicates to O: 1:2 in frameworks, 2:5 in sheets, 1:3 in single chains, 4:11 in double chains, x:3x in rings, and 1:4 in orthosilicates. The students must memorize, or better yet, be able to derive, all these ratios, the reason being that once these are known, its subgroup could be determined given any complex chemical silicate chemical formula. I continue to stress that the subgroups give clues to the physical properties. For instance, optically, the framework silicates, whose structures are basically the same in three dimensions, have low birefringence, while the sheet silicates have low birefringence within (001) and higher birefringence perpendicular to it. Also, any chain silicate will tend to be elongated parallel to the chain. Of course, there are exceptions to these general rules, but this gives the students a starting point to see how the physical properties relate to the crystal structures.

After starting with the framework silicates and discussing depolymerization of the silicate tetrahedron and substitutions of Al for Si, the stage is set to continue through the silicates. For the sheet silicates tetrahedral and octahedral layers are used as the basic building blocks, and they learn that as Al substitutes for Si in the tetrahedral layer, charge balance is needed with an inner layer cation. (This is similar to Al substitution for Si in feldspars with charge balance being maintained by Na, K, or Ca.) Next, I discuss the chain silicates, ring silicates, and finally the orthosilicates. The basic building blocks and the fact that charge balance must be maintained in each group are stressed. For example, a continuum occurs between single chain silicates and sheet silicates when two single chains join side by side to form a double chain and, in turn, when an infinite number of single chains join side by side to form a sheet. See the notes section in Gunter (1996) for details of how this material is covered. The main point throughout the lectures is to show how each group is related to the other and, most importantly, how the physical properties of the minerals are related to their crystal structures.

Field trips - Latah County mineral collection

Mineralogy, like most subdisciplines in the geosciences, must incorporate field trips into the class. The field trips must have a goal and not merely be a superficial tour of the outdoors. In the mind of a non-mineralogist, probably the major goal for mineralogy is for the students to be able to identify minerals in hand specimen in the field. This, of course, is best done with mineral collecting field trips. Minerals can be collected and identified in the field based upon their physical properties and associations and confirmed in the lab by use of other analytical methods, the simplest of which is the petrographic microscope where, by a quick check of refractive index by the immersion method or the optical class of a mineral one can confirm a mineral's identify. Other more advanced analytical methods such as powder x-ray diffraction or electron microscopy (for chemical analysis) can also be used, if available. The more advanced methods should not be relied upon solely because the students may not have access to them later in their careers. However, the entire process begins in the field.

We are fortunate in northern Idaho to have sites with excellent, diverse geology. Within our county we have outcrops of metamorphic rocks (the Belt rocks, which have been intruded and altered by the Idaho Batholith) and exposures of the Columbia River basalts, which contain some interbedded sediments. (To take a "virtual field trip" in northern Idaho, see Gunter, 1996.) We also have world class mineral collecting sites, where our state gemstone - the star garnet - gold, beryl, tourmaline, and large books of muscovite can be found.

During the semester we take two one-day field trips on weekends and visit several of the local mineral collecting sites. After we have competed the trips, another weekend is set aside for more detailed lab analysis of the minerals, with assistance from the TA and me. The students are encouraged to check the mineral identification by using grain mounts with the petrographic microscope. We also use a scanning electron microscope (equipped with an energy dispersive system) for qualitative chemical analysis and a powder diffractometer if we are unsure of the mineral's identification, based first upon its physical properties and secondly its optical properties.

The students are required to assemble a mineral collection from these field trips. For each mineral they must list its location, name, chemical formula, and how they identified it, and they must provide a small sample. The students are allowed to keep the mineral collections and use them in later classes and field camp to help identify minerals in local rocks.

Incidentally, this entire project developed into a master's project, so we have now obtained more precise mineral descriptions, maps to locations, and new locations (Rossenbach, 1994). Much of the data from this project was used to build a multimedia program (originally in Astound for the Mac, but recently ported to the Web, Gunter, 1996), so the students can go out on their own mineral collecting trips, which many of them do.

Student assessment

Another difficult aspect of any course is determining how much the students learn and assigning grades. Testing should be a learning experience, either forcing students to study or requiring them to think through a certain problem. I use a series of quizzes, problem sets, tests, and lab and lecture projects to assess the students. The 1000-point breakdown is as follows: 11 lecture quizzes, 220: 13 lecture problem sets, 130: 2 lecture tests, 200: paper and talk, 50: laboratory, 300: Latah County mineral collection, 50: class and laboratory participation, 50.

The weekly quizzes are given in lab and require the students to stay current with the material being presented and to integrate several sections of the course. Each quiz consists of a memorization section and an application of that knowledge to demonstrate some mineralogical concept. For instance, they may be asked to give the chemical formulas for the end-member feldspars and 1:1 layer silicates. Then they are asked what 1:1 layer silicate each feldspar might form upon weathering. Given that information they then can hopefully make the connection that feldspars weather to form sheet silicates. The weekly problem sets are similar to the quizzes, but require more time to complete. By a combination of the quizzes and the problem sets the students seem well prepared to take the two tests given in the class.

The remainder of the grade for the course is based upon projects and the lab. Thirty percent of the grade is based upon weekly lab quizzes and assignments. The details of this breakdown varies depending upon the graduate student who teaches the lab. Each student also gives a brief 15-minute talk (in lab) and writes a 2- to 3-page paper on a non-silicate mineral group. The students are also graded on their county mineral collection.

Course evaluation

I have used the current format for teaching mineralogy for three years, with minor refinements based upon student evaluations. Two evaluative tools are used in the course: the required end-of-semester university evaluation and an evaluation that I administer four weeks into the semester. This second evaluation is completely narrative, like the first, is anonymous. I ask the students a few basic questions, such as "What can be done to improve the course?" and "What aspect do you like most (and least) about the course?" Their responses are typed by our secretary and then given to me.

The main, and basically only, recurring complaint from the students is the need to memorize chemical formulas; however, as I tell them, they must know a few of the really important mineral formulas. Overall, they also comment about the large amount of work but accept this as a necessary requirement to understand mineralogy and preparation for their other geoscience courses.

Other anecdotal forms of evaluation also exist. Both the hard and soft rock petrologists in the department feel the students who complete my course have good skills in mineral identification with the petrographic microscope. However, I have received a complaint from the professor who teaches field camp. He claims the students are more interested in the minerals than the rocks!"

Conclusions

Mineralogy should both be taught as more than just a means to an end. Silicate minerals compose 92% of the earth's crust and should thus be given a considerable amount of time in the class. The relationships between a mineral's physical properties and crystal structure cannot be over stressed. My course is probably weighted a little heavy toward crystallography and optical mineralogy; this is natural, as these are my specialties. There is no single set of content for a mineralogy course, or for that matter, any course; the individual professor should tailor the course based upon his/her expertise, equipment available, and geological setting. Based upon student feedback and success in later classes, I think my mineralogy course has met its goals.

Mineralogy should continue to be a central component in geoscience education and should remain a rigorous course that includes study of crystallography and crystal chemistry. We must not abandon years of work that have revealed the systematics of minerals and their crystal structures. It is from teaching this material that students can appreciate the properties and behavior of minerals at a theoretical level, and not just memorize, for example, that feldspars have low birefringence.

Acknowledgments

I was very fortunate to attend graduate school at Virginia Polytechnic Institute and State University, where I was mentored by three of the finest mineralogists ever - F.D. Bloss, G.V. Gibbs, and P.H. Ribbe - and I would like to thank them for their advice, encouragement, and many hours of excellent lecturing in mineralogy. More recently, John Brady (Smith College) and Dave Mogk (NSF and Montana State University) have provided personal motivation as well as demonstrating professional leadership at the national level to improve the teaching of mineralogy. The original idea for the county mineral collection was borrowed from Bill Hood, who taught mineralogy at Southern Illinois University. NSF-DUE #9254158 provided partial support for completion of the Latah County Mineral collection project. The purchase of the powder diffractometer was made possible through grants from the Murdock Charitable Trust and NSF-DMR #9301402.

References

Bloss, F.D., 1961: An introduction to the methods of optical crystallography. Holt, Rinehart and Winston, New York, 294 pp.

Bloss, F.D., 1971: Crystallography and Crystal Chemistry. Holt, Rinehart and Winston, New York, 545 pp.

Brady, J.B., 1995: Confessions of a Mineralogy Professor. Geotimes, September, 4.

Brady, J.B., Newton, R.M., and Boardman, S.J., 1995: New uses for powder x-ray diffraction experiments in the undergraduate curriculum. Journal of Geological Education, v. 43, 466-470.

Brady, J.B., and Boardman, S.J., 1995: Introducing mineralogy students to x-ray diffraction through optical diffraction experiments using lasers. Journal of Geological Education, v. 43, 471-476.

Dowty, E., 1993: ATOMS: A computer program for displaying atomic structures. Shape Software, Kingsport, Tennessee.

Gunter, M.E. and Downs, R.T., 1991: DRILL: A computer program to aid in the construction of ball & spoke crystal models. American Mineralogist, v. 76, 293-294.

Gunter, M.E., 1992: Optical Mineralogy. Encyclopedia of Earth System Science, W.A. Nierenberg, editor, Academic Press, Inc., San Diego, 3, 467-479.

Gunter. M.E., 1996: Mickey's Web Page. http://www.uidhao.edu/~mgunter.

Klein, C. and Hurlbut, C.S., 1993: Manual of Mineralogy, 21st Edition. John Wiley & Sons, Inc., New York, 681 pp.

Neese, W.D., 1991: Introduction to Optical Mineralogy, 2nd Edition. Oxford University Press, 335 pp.

Rossenbach, R.M., 1994: Minerals of Latah County. Masters Thesis, University of Idaho, Moscow, Idaho.

About the Author

Mickey E. Gunter received his B.S. in geology, with a minor in mathematics, in 1979 from Southern Illinois University at Carbondale, and M.S., 1982, and Ph.D., 1987, from Virginia Polytechnic Institute and State University. Currently, he is an associate professor of mineralogy in the Department of Geology and Geological Engineering at the University of Idaho, teaching beginning geology, mineralogy, and integrated science, and conducting research in mineralogy, optical crystallography, and health effects of mineral dust.