Abstract
An interactive computer system has been developed in order to assist in mineral identification under the petrographic microscope. The present reference file consists of optical and chemical properties of about 150 mineral species. The properties are name, chemical formula, refractive index, birefringence, indicatrix, optical angle (2Ω), extinction angle, elongation, pleochroism, and color in each of the X-, Y- and Z-directions of each species. The system utilizes optical properties of an observed mineral given by a user, and reduces the number of possible minerals. This procedure is essentially the same as using published mineral identification tables except that the process runs in a personal computer. The system presents a series of questions to a user, and the user selects any of the prepared answers according to his observation. The user can also choose any desired question independently of the sequence. When a user has chemical and/or mineralogical data for a sample, the user can provide the information to the system at any step of the identification process. In order to assist a user the system prepares some explanations and suggestions for the questions about some optical properties, such as refractive index, indicatrix, color, elongation and extinction angle of anisotropic minerals, and optical angle of biaxial minerals. This feature is quite different from the conventional identification table.
