The Spanish Mines

In the 13th Century B.C. the Phoenicians, then an enterprising and rapidly growing nation of traders and mariners, ventured into the Atlantic and established Cadiz (1240 B.C.). They soon spread a short distance inland to Huelva, where they discovered and began to work an enormous mass of cupriferous pyrite which is still the largest of its type in the world, although it is now regarded primarily as a source of sulfur. Subsequently the deposits at Rio Tinto and the neighboring Tharsis became one of the most important sources of copper; and after the Romans had conquered Carthage in the First Punic War they occupied all Spain and seized the mines.

Originally most metalliferous mines were simply open trenches or slight excavations into hillsides. Then sloping tunnels or adits followed which provided both ingress for the miners and a way out for the product, besides an easy means of dealing with the ever-present hazard of mine water. The Romans, with their genius for engineering, improved on these methods considerably, particularly in Spain, where they reduced a hill impregnated with copper ore into a valley. Their method of breaking up the rocks was to heat them by fire and then to throw cold water over them to cause disintegration by rapid cooling. Deep shafts were dug, their walls lined with timber and waterwheels were employed for drainage; several scores of these wheels still survive. The pattern of the wheel was essentially the same as the Egyptians had already used for over two thousand years to draw irrigation water from the Nile. The Roman mines had at least thirty of these wooden wheels which revolved on bronze spindles made from an alloy of 91 1/2 percent copper, 6 1/4 percent tin and 1 3/4 percent lead. Buckets were placed on hooks at the end of each spoke. The usual number in most cases was twenty-four per wheel. A wheel was worked by slaves after the manner of a treadmill, and each raised the water about 10 feet. The miners descended into the pit by stepping stones driven into the wall, the holes for which still survive.

The Romans actually succeeded in carrying one working down to a thousand feet below the surface, some shafts having a 40-degree raise. Down below, light was provided by means of oil lamps with special wicks. By their underground workings, this remarkable people are stated to have uncovered nearly one hundred lenses of the ore.