These olive oil lamps are made of copper and bronze. The fire patina coloration is formed at 1500 degrees as the parts of the lamp are fused together, making no two lamps exactly alike. Copper Copper is the best common element to use as a heat absorber. The flame's energy is absorbed through the wick stem and conducted on down into the dish. The oil temperature is hottest at the top of the wick tube, and coolest at the bottom.
Hotter oil is lighter and rises to the flame, drawing in new cooler oil at the bottom of the tube.
A pump action is started, which delivers more oil than can be burned. The action allows longer burning times by letting the oil reservoir be deeper. Copper makes all this possible. The copper is not polished because fine particles are generated in the process of polishing. Fine copper particles find their way into the ground water and eventually make it to the ocean, killing algae and zoo plankton.