An Introduction to the Analysis of Clay minerals by Laser and X-Ray Diffraction TechniquesStephen Guggenheim (2002) An introduction to the analysis of clay minerals by laser and X-ray diffraction techniques: In CMS Workshop Lectures, Vol. 11, Teaching Clay Science, A. Rule and S. Guggenheim, eds. The Clay Mineral Society, Aurora, CO, 143-160.
Stephen Guggenheim (2002) An introduction to the analysis of clay minerals by laser and X-ray diffraction techniques: In CMS Workshop Lectures, Vol. 11, Teaching Clay Science, A. Rule and S. Guggenheim, eds. The Clay Mineral Society, Aurora, CO, 143-160.
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Stephen Guggenheim, 2002. "An Introduction to the Analysis of Clay minerals by Laser and X-Ray Diffraction Techniques
Stephen Guggenheim (2002) An introduction to the analysis of clay minerals by laser and X-ray diffraction techniques: In CMS Workshop Lectures, Vol. 11, Teaching Clay Science, A. Rule and S. Guggenheim, eds. The Clay Mineral Society, Aurora, CO, 143-160.
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Abstract
Required materials: Red laser pointer, green laser pointer, gratings labeled #1 through #6, metric rule, extra batteries, tape measure (metric or in inches)
Examine Figure 1. Both parts of the figure are obtained by using X-rays. Figure 1a is a medical X-ray film, obtained from a dentist's office, whereas Figure 1b is an analytical X-ray film. Can you explain how X-rays were used to obtain each film?
The purpose of this laboratory is to examine the properties of diffraction (Part 2) and then to use diffraction to identify some clay minerals (Part 3). Part 2 utilizes light diffraction from gratings made of nylon strands woven together; a common use for such gratings is in filtration devices, such as sieves. Light is used here as an analogue for X-rays. Both radiations are part of the electromagnetic spectrum and are essentially identical in diffraction behavior. In contrast to X-rays, however, light is less dangerous, easy to manipulate, and very inexpensive to generate. The use of gratings is also an analogue. The gratings used here are two-dimensional networks of nylon strands, in this case, whereas crystals are submicroscopic gratings that are generally three-dimensional in nature as defined by atoms.
The geometry of diffraction, or the positions of the diffraction spots (often referred to as peak maxima, diffraction peaks, etc.) is related to the repeating motif. For example, Figure 2a shows
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Teaching clay science

The teaching of clay science is often thought of as forming the curriculum of an upper-level college course for juniors, seniors and graduate students. Although clays and clay minerals are complex subjects often requiring extensive background to understand in detail, introducing topics related to clays does not require such specialization. Furthermore, clays are a part of modern everyday life, being found in common household products (from toothpaste, toilets, and cat litter to paper, plastics, and fine china). It does not seem reasonable to wait until a student reaches the upper-college level to introduce the subject, although the introduction of clay science must be approached at levels appropriate to the student's development and background. In fact, one of us (A. Rule) has successfully introduced crystallography concepts of crystal shape and symmetry, and has taught lessons in the industrial uses of clay minerals at the primary-school level. Education scholars have developed procedures for teaching that closely parallel the way humans learn. For the most part, these instructional practices have not been implemented at the college level, although such teaching methods could easily be applied to benefit college-level students. The idea of a Teaching Clay Science Workshop was developed over the last three years to integrate the efforts of education scholars, high-school teachers and college professionals toward improving clay-science instruction. This integration of learning theory with clay-science teaching has produced a unique set of example lessons, which resulted in this volume of Workshop Lectures. Finally, we express our appreciation to P. Schroeder for taking our edited manuscripts and organizing them to conform to the CMS Workshop Lectures Series. Also, we thank M. Krekeler for working through all of the laboratories presented here and for providing his comments to the authors.