『Abstract
Here we introduce a technique for simultaneous measurement of
surface normal retreat rates of specific cleavage faces by vertical
scanning interferometry and the bulk dissolution rate of a mineral
powder. A hydrothermal reactor is used to contain both a well-characterized
powder and oriented single crystals with a masked reference surface
at elevated temperatures. We show examples using both anorthite
and albite reacted at temperatures between 150 and 200℃. In the
case of albite, dissolution rates of fine-grained powders are
substantially enhanced compared to those prevailing on large single-crystal
cleavage surfaces. Rates developed on the (010) albite cleavage
surface are also substantially faster than those on the (001)
face, where etch-pit development was relatively modest and surface
normal retreat was not detectable within the time frame of the
experiment. The reasons for this difference are not immediately
clear, but may be related to anisotropy in the distribution of
Al-O-Si vs. Si-O-Si bonds in the albite structure, (010) twinning
expressed on the (001) surface, and possible disruption of kink
propagation across the twin plane.』
Introduction
Method
Ex situ VSI and reactor assembly
Albite and anorthite dissolution runs
Results and discussion
Anorthite
Albite
Concluding remarks
Acknowledgments
References cited