IV.—Superheated Water

Extract

The abstract in the Geological Magazine of Professor Beck's paper on ore veins and pegmatites is of great interest to myself, as it deals with two points which I pressed on geologists in 1894 and earlier, viz., the crystallisation of vein-minerals out of superheated water, and the doubtful origin of that water. The special difficulty is raised by the Dartmoor veins, as the water they contain, together with the granites, is sometimes salt and sometimes fresh, and is of all degrees of original supersaturation. I wrote as follows:

‘The question as to the marine or plutonic origin of the brineinclusions referred to is of transcendent importance in connection with the question as to whether the water ejected by volcanoes is of meteoric or marine origin, of derived from the interior magma’ (Geol. Mag., 1894, p.99).