Chemical composition of synthetic, boron-rich haplogranite glasses from electron microprobe and confocal Raman spectroscopic analyses

The coordination environment of boron in silicate melts and glasses strongly affects their physical properties and has been extensively studied in industrial glasses. Boron coordination in natural glasses and magmas is less well known, particularly regarding its dependency on melt composition. To investigate this dependency, we synthesized a set of haplogranite glasses, analogous to natural leucogranites, for determination of the boron coordination by nuclear magnetic resonance (11B MAS-NMR). The starting glass was water-free haplogranite, prepared to the composition expressed Ab40Or25Qz35, where Ab, Or and Qz represent the components albite, orthoclase and quartz, resp. This glass was modified by adding different contents of boron (2 and 5 wt.% B2O3), different water contents (0, 4 and 6 wt.%), and modifying the ratios of Al to the alkali elements Na and K. This ratio is expressed by the “alumina saturation index” or ASI (= molar ratio Al2O3 / (CaO + Na20 + K2O). The data set provided here contains the results of in-situ analyses for major elements by electron microprobe and by confocal Raman spectroscopy for water concentration.

The over-riding goal of the DFG priority programm 2238 - DOME (https://www.uni-potsdam.de/en/spp2238/) is to find solutions to fundamental questions of element transport and mineralization in heterogeneous chemical systems that are complex, dynamic and highly transient. The topic of ore genesis has been studied for a long time from a combined field/laboratory perspective and also experimentally in simplified systems, but rarely have these techniques been integrated in a coordinated way with the third perspective from numerical process modeling. The originality and innovation potential of this priority program lies in the coordination of empirical field-related studies that define the geological/mineralogical framework of natural ore systems with experimental work and numerical models that provide a quantitative understanding of the processes involved.