GEO.Crystallography


The problem 

Developments are under way to teach an option course in crystallography more or less entirely via networking. Crystallography is a subject which traditionally poses difficulties at highschool level, mainly because it is difficult to provide the practical teaching required to make it sufficiently interesting to the student and for a full understanding of the main topics. As a result relatively few students express interest and those who do are seldom offered courses. This is to be regretted, especially in view of the current scientific re-awakening in the subject in connection with semi conduction and super conduction technology.

The solution?

Computer technology and networking provide a new opportunity to teach crystallography at highschool level. Simulations and interactive information technology are ideal tools for teaching the techniques and principles required, often on a one-to-one basis.

Some samples of computer work involving geology 252, an option course dealing with basic principles of crystallography, such as crystallization, optical properties (refraction,polarization etc.) and crystal structural chemistry are shown here. The work includes digitized microscope images of crystals grown by students.

Top

 

Crystallization experiments

Growing crystals in containers from saturated solutions is a very useful way of illustrating important concepts such as crystal faces, crystal habit, constant angles between faces and faces of growth. However, preparation times and the relatively large amounts of materials involved often mean that such experiments are only rarely carried out at highschool level with the result that this aspect of crystallography courses tends to be treated only theoretically and as a result, often fails to arouse student interest in what is both an exciting and highly relevant science topic.

An alternative way of illustrating crystal growth involves the use of a polarizing microscope, a video camera and a video digitizer board or image grabber. The heat from the microscope´s illuminator source causes small drops of saturated solutions on slides to become oversaturated and minute seed crystals gradually grow. The basic equipment required is shown below:

At Hamrahlíð College the progress can be monitored on both a large TV screen (and via a video projector) as well as the computer screen. Images can be grabbed at intervals and stored on disc, to be arranged later and analysed. Some sample images of compounds from several crystal systems are shown below in both plane polarized light and under crossed polarizers. (Georg R Douglas)

Click the image for full size version.

Top


These pages are maintained by Dr Georg R Douglas, Hamrahlíð College, 105 Reykjavík, Iceland.