When Cyprus was spreading in the Tethyan floor, seawater descended through fissures and--close to or within the magma--picked up quantities of dissolved copper, and lesser amounts of mercury, manganese, tin, silver, and gold. Like the black smokers active now in the Red Sea and the Gulf of California, hot brine plumes rose through the Cypriot rock and precipitated metals and metallic compounds on the pillow lavas. From everywhere in the ancient world, people turned to Cyprus for weapons-grade coppper. The swords, spears, and shields of innumerable armies were made from Cypriot copper. Before long, though, the resin-reduced metals were gone. More than a millennium passed before the Cypriots learned that dark earths where the metals had been were not a whole lot less cuprous than the metal itself. Rainwater--rare in Cyprus on the human scale but continual in geologic time--had removed lighter materials and had concentrated the copper minerals malachite and azurite in an upper zone of extreme high assay. Geologists of the twentieth century would describe such a concentration as a supergene enrichment. The ancients somehow discovered that if they mixed the cuprous earth with umber, and then heated the mixture, molten copper with flow. There was plenty of umber close at hand. Umber is an oxide of manganese and iron. In spreading environments on ocean floors today, umber is piling up on the pillow lava in large dark-chocoloate cones beside the black smokers, as it did on the pillows of the nascent cyprus.

Annals of the Former World By John McPheePage 516