A New Computer Supporting System to Describe Zircon Crystal Forms

Abstract

A new system to describe zircon crystal forms has been developed. After measuring the thickness and the size of a crystal, four indexes are calculated: flatness, elongation, prism, and pyramid.
There are two basic forms for a zircon crystal according to the projected plane: either the {100} or {110} prism face. The prism face parallel to the projected plane is called “middle”, since it is located in the middle of the projected form. A projected form is classified into Type 100 or Type 110 based on the “middle”prism face, because each type has defferent equations.
The crystal faces observable from one direction are assumed to be the same size as those onthe opposite side. The vertical distance is called “height”, and the horizontal distance “Width”. The crystal “thickness”is measured under a microscope by focusing first on themiddle prism face and then on the surface of the glass slide on which the zircon crystals are scattered. The crystal sizes required for the calculation are: crystal height, crystal width, middle prism width, middle prism height, left and right prism heights of the outline, and left and right prism heights of the middle prism. The results ca be shorn on a table or on fourkinds of figures.
Requirements: PC-9801 computer with 640K main RAM, high resolution monitor, A5 size digitizer, plotter and printer.