C. Dorronsoro1; A. García Navarro2; A. Bravo3
1. Depart. Edafologia. Facultad de Ciencias. Universidad de Granada. Spain.
2. Depart. Edafología. Facultad de Ciencias. Universidad de Extremadura. Badajoz. Spain.
3. Depart. Edafología. Facultad de Farmacia. Universidad de Salamanca. Spain.

This programme studies the theoretical aspects of the optical properties of transparent minerals and teaches the user how to evaluate each of these properties just as he would in the identification of minerals using the petrographic microscope. The properties analysed are the usual ones: relief “n”, colour, pleochroism, habit, cleavage, interference colour (birefringence), extinction angle, sign of elongation, interference figure (optic group and optic sign).

The programme runs on any Apple Macintosh personal computer, but a version could shortly be available for PCs using Windows. The programme has been developed in HyperCard 2.2 with color tool.

The program is a combination of texts, figures and corresponding microphotographs and movies, taken under different working conditions (polarised light, with and without analyser; orthoscopic and conoscopic illumination. After presenting the corresponding images, a series of questions are given concerning the identification of the mineral, intended to check how much the student has assimilated.

The immediate availability of microscopic images representing the various minerals reduces learning time to a minimum. The number and quality of the images and the extremely rapid manipulation of information makes this technique particularly suitable in providing a personalised and highly efficient means of learning.

This programme, when used in conjunction with traditional practicals using the optic microscope, frees the teacher from routine and repetitive work, and reduces the maintenance expenses of optic equipment (microscopes and accessories) and material (microscopic materials) to a minimum.