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It seems impossible that all these diversified materials should have been derived from the same source, and the only rational explanation of the phenomena is that which I have heretofore advocated, the ascent of metalliferous solutions from different and deep seated sources.
From Thasos in the East, where Herodotus saw "a large mountain turned topsy-turvy by the Phoenicians in their search for gold," to the Scilly Islands in the West, where workings attributable to them are still to be seen, all the metalliferous islands and coast tracts bear traces of Phoenician industry in tunnels, adits, and air-shafts, while manufactured vessels of various kinds in silver, bronze, and terra-cotta, together with figures and gems of a Phoenician type, attest still more widely their manufacturing and commercial activity.
Do the great cavities, which are exclusively called caverns, owe their origin to the same causes as those which have produced the lodes of veins and of metalliferous strata, or the extraordinary phenomenon of the porosity of rocks? Do grottoes belong to every formation, or to that period only when organized beings began to people the surface of the globe?
Although we are led to infer, from the foregoing reasoning, that there has often been an intimate connection between metalliferous veins and hot springs holding mineral matter in solution, yet we must not on that account expect that the contents of hot springs and mineral veins would be identical.
Thus in soluble rocks, such as limestones, joints enlarged by percolating water are sometimes filled with metalliferous deposits, as, for example, the lead and zinc deposits of the upper Mississippi valley. Even a porous aquifer may be made the seat of mineral deposits, as in the case of some copper-bearing and silver-bearing sandstones of New Mexico.
Other kinds of moist formations, both metalliferous and non-metalliferous, may influence the lines of least electrical resistance, besides those containing the particular metal which is being sought for. The water difficulty has enforced the abandonment of very many valuable mines in which the positions of the lodes are still well known.
I linger a moment to gaze upon the painted warrior spurring his wild steed along thy banks to gaze upon the Dacotah girls bathing their lithe limbs in thy crystal wave then on again past the "Cornice Rocks" the metalliferous shores of Galena and Dubuque the aerial tomb of the adventurous miner.
The steaming water rises through fissures in volcanic rocks and is now depositing in the rifts a vein stone of quartz, with metallic ores of iron, mercury, lead, and other metals. RECONCENTRATION. Near the base of the zone of solution veins are often stored with exceptionally large and valuable ore deposits. This local enrichment of the vein is due to the reconcentration of its metalliferous ores.
At the mouth of the valley of Canota, and at several points northwards, there is an extensive formation of a glossy and harsh, and of a feldspathic clay-slate, including strata of grauwacke, and having a tortuous, nearly vertical cleavage, traversed by numerous metalliferous veins and others of quartz.
The usual method of generating heat is by the combustion of some fuel, such as coal, coke, gas or oil, and this has been utilized for hundreds of years in smelting metals and ores and in refining the material from a crude state. Now it may happen that a nation or region may be rich in metalliferous ores, but possess few, if any, coal deposits.
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