Haralson County mining history exhibit 2008:
Using science to identify gold




How do you distinguish gold from base metals when the individual sample pieces (no matter how massive in aggregrate) consist of too few atoms to recognize such samples visually, even with the best optical microscope? Embedded below, a videotaped MIT OCW (q.v.) course 3.091 lecture explains how we can use x-ray diffraction to establish the identity of crystalline solids.

The video starts with a short pointless diversion on a piece of historical period music, followed by a shameful admonition for the students taking the course to respect the mandated study protocol. Finally, the actual lecture topic is addressed for the vast majority of the video. A charming "human interest" postscript touches on the application of x-ray examination beyond chemical analysis.

At points in the video, one is referred to written lecture notes one can find here.

(Aside to distance learning professionals: Note that copyright clearance is simply sidestepped when needed by expurgating the visual and auditory materials at issue.)


This writer is grateful to Professor Sadoway for subtly delivering the very timely message that there are causes of enduring benefit to humanity for which people with special talents might reasonably risk or lose their lives, and causes for which they might not.

MIT OpenCourseWare (OCW) provides an opportunity for students who are highly motivated and well-prepared to study demanding university-level subjects on their own over the Internet, using materials developed at the Massachusetts Institute of Technology (MIT), entirely free of financial payment to MIT.

Other universities with OpenCourseWare efforts.

All online materials for 1800 MIT OCW courses. Of likely special interest to readers of this page are the online materials for course 12.001: Introduction to Geology (Spring 2008).

Single-course video playlists for a wide variety of elementary (and some other advanced) courses. Of likely special interest to readers of this page is the video playlist of 34 videos for course 3.091: Introduction to Solid State Chemistry (Fall 2004), a single video from which is embedded above. (Professor Sadoway provides a seven-minute overview of his course here.)

High school students and teachers should also explore Highlights for High School.