Tourmaline composition as a guide to mineral exploration; a reconnaissance study from Nova Scotia using discriminant function analysis

Abstract

Tourmaline has an extensive range of solid solution that can potentially reflect the nature of its coexisting phases, including some minerals of economic interest. In this study, tourmaline compositions are considered in the framework of two hypothetical classes of mineral deposits to evaluate the use of tourmaline chemistry to assess economic potential. Tourmalines from 27 known mineralized and barren localities in Nova Scotia were analyzed by electron microprobe for their major elements and by inductively coupled plasma mass spectrometry for their boron isotope compositions. Linear discriminant function analysis of these data on a two-group (mineralized and barren) basis correctly classified 85 to 89 percent of the tourmaline samples. Similarly, linear discriminant function analysis on a three-group (nongranite mineralized, granite-related mineralized, granite-related barren) basis correctly classified 72 to 85 percent of the tourmaline samples. Quadratic discriminant function analysis resulted in even better discrimination. These preliminary results suggest that this type of geochemical-statistical approach is promising for mineral exploration.