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Abstract--Batch reactor experiments were performed at 150~ 175~ and 200~ to determine the effect of high pH NaOH solutions on the mineralogy of the Opalinus shale. In these experiments, the change in solution quench pH at 25~ solution composition, and mineralogy were monitored as a function of time for up to ~40 days. Runs were performed in 50 ml titanium hydrothermal reactor vessels. Each reactor was charged with 0.5-5.0 g of the 80-200 mesh size fraction of Opalinus shale, and 25 ml of solution (0. l and 0.01 M NaOH). The general sequence of reaction products observed under these high pH conditions include first the formation of analcime, followed by vermiculite, and finally Na-rectorite formation.

Abstract--Batch reactor experimertts were performed at 150"C, 175~ and 200~ t~ determine the effect of high pH KOH solutions on the mineralogy of the Opalinus shale. In these experiments, the change in solution quench pH at 25~ solution composition, and mineralogy were monitored as a function of time for up to ~50 days. Runs were performed in 50 ml titanium hydrothermal reactor vessels. Each reactor was charged with 0.5-5.0 grams of the 80-200 mesh size fraction of Opalinus shale, and 25 ml of solution (0.08 and 0.008 m KOH). Under these high pH conditions, the general sequence of reaction products observed is the formation of phillipsite, followed by K-feldspar + K-rectorite. Phillipsite is a metastable intermediate that eventually transforms to K-feldspar. This sequence of mineral reaction products is very different from that found in the NaOH system.