RUI: Crystal Growth Speedometry, Micro-Fourier Transform InfraRed (FTIR) Spectroscopy of Minerals

University Of Wisconsin-Eau Claire, Eau Claire WI

Investigators

Abstract

Abstract EAR-0126285 Ihinger University of Wisconsin-Eau Claire The primary objective of this proposal is to use H-species defects, incorporated into hydrothermal crystals during crystallization, to determine the relative growth rates of different crystallographic faces, which in turn may be used to derive the absolute time for in situ crystal growth, with appropriate experimental calibration. Quartz and kyanite will be investigated. The timescales involved in crystal growth processes are poorly constrained and the absolute time involved in the growth of crystals from either igneous or metamorphic environments is not known. This is a first order problem in petrology and few new approaches have been proposed to attack it. Although the theory describing reaction kinetics in the crustal environment is sound, few quantitative studies exist and the mechanisms responsible for the variation in size and shape of individual crystal faces are still not well understood. Published data on natural euhedral quartz crystals obatined in our laboratory allow quantitative determination of the relative growth rates of their growth faces throughout their growth histories. The concentration of water molecules and metal hydroxyl impurities incorporated into the crystal structure at the time of growth serve as "speedometers" that directly reflect the growth kinetics of active growth faces. These measurements provide a new means of imaging the shape and absolute dimensions of crystals throughout their growth history. A partnership with commercial quartz production company will provide synthetic samples for experimental calibration of fluid parameters, which are necessary to quantitatively interpret H-defect data from natural hydrothermal quartz crystals.