Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

Although the size and shape of crystals in thin sections have been measured in a number of studies, it has not been possible so far to calculate from these data the true, three-dimensional shape and size of the crystals. A numerical model, based on orthogonal solids, has been developed to attack this problem. This model shows that crystal habit can be calculated from width to length ratio distributions for most crystals in massive rocks and for all crystals in laminated or lineated rocks. Variations in the habit of minerals can reveal aspects of the physicochemical conditions of crystallization. The same model has also been used to develop the equations necessary to transform two-dimensional crystal size istributions into true crystal size distributions. Corrections for the cut effect and the intersection probability effect both require a knowledge of the crystal habit.