If crystals are the flowers of the earth beneath, metals are unquestionably mineral trees in gradual development, and dependent upon certain acids, alkalies, and other materials, for sources of their transformations. Moisture seems essential for these chemical changes. The production of gold is observed to take place chiefly towards the surface, though at a considerable depth in the compact rock very minute particles may be detected. When the crystalline rock disintegrates, iron sand is developed and accumulated. Mr. Hopkins, of the Port Phillip Gold Company, the ablest practical mining geologist of the day, and who calls clay slate “_oxidated crust of granite_,” observes, that it is “within the limits of this transition of the crystalline base into the oxydated compound that the minerals become principally developed in veins, &c.” An interesting illustration of this is afforded at Specimen Hill, Bendigo, where the metal lies between the quartz and the slate. Again, at Clunes, the fissures in the quartz are filled with greasy red earth, highly impregnated with iron, and in this was the gold. Sir T. L. Mitchell, in his most interesting report, tells us, that the gold of Summerhill Creek was “in incrementitious portions and separate increments of quartzose crystals.” In fact, the metal is often detected in considerable masses in the solid rock apart from any veins, which could not be, unless formed in the very place. It is not often, however, that a lump of 106lbs, as at Louisa Creek, is found thus detached.