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Lithium minerals, petalite (Li[AlSi4O10]) and lepidolite (K2(Li, Al)5-6[Si6-7Al2-1O20](OH, F)4), were reacted with seawater and NaCl solutions for 240 hours at 150 to 250°C and with a water/mineral ratio of 25 by weight, to clarify the role of dissolved salts on the enrichment of lithium in natural saline waters such as coastal thermal waters and fossil seawaters. Lithium leaching from the minerals was enhanced with increasing salt concentration and temperature. It was proved from the experiments using various salt solutions that NaCl solution and seawater are effective for the leaching of lithium from rocks and that even the altered seawaters containing low magnesium have the ability to extract lithium from rocks. This investigation suggests that the non-volcanic saline waters of high lithium content (e.g. fossil seawater) can be produced by a long term seawater-rock interaction at relatively low temperature without a contribution from the so-called “magmatic emanation”.

The study reported in this paper concerns the role of salts in dissolution of powdered quartz. Kinetic dissolution experiment was carried out in acid media at 60 and 90°C to know the mechanism of acid alteration of rocks. The dissolution rate of silicon was accelerated by addition of such salts as sodium chloride and sodium sulfate in solution above about pH 2 but not affected below about pH 2. An accelerating effect of divalent sulfate ions was greater than that of monovalent chloride ions. Moreover, this effect became remarkably greater with increasing concentration of salts, increasing temperature and increasing pH value from 2 to 4.