Metallurgy covers all processes involving native metal or metallic ores after mining (concentration, smelting, refining) up to the production of artefacts. Understanding these depends less on literary references (mainly Roman: Strabo, Pliny (1)) than on archaeological and scientific research, analytical, comparative, and experimental. Only the richest ores could be smelted directly; generally, enrichment was needed to avoid wasting fuel. So, mined rock was sorted underground and above, poorer material rejected, and the richer crushed with stone mauls or iron hammers on anvil-stones; deeply worn boulders are recognizable as such in Laurium. Washing aided concentration of ores, especially those (gold, argentiferous lead) heavier than gangue; it could be done in pans or cradles, with rough cloth or fleeces (as in Colchis, giving rise to the golden fleece legend). Milling to a fine grain, in rotary mills or hopper-querns, and sieving preceded washing. Laurium best exemplifies the elaborate arrangements for ore treatment which local conditions necessitated. Stone-built cement-surfaced rectangular washing tables had stand-tanks with funnelled jet-holes (perhaps serving wooden sluices), level floors, sunken channels, and sedimentation basins, which separated the milled ore from gangue and recycled water. There are also four known round washeries with helicoidal stone sluices. Repeated washing ensured the desired enrichment. Smelting was done with wood or carbon fuel in ovens of various forms, with heat intensified by means of bellows. Laurium offers five furnace sites, three excavated with a row of banked oven-rooms, filling-platforms, and traces of stone and clay chimney-ovens. Furnace techniques depended on the melting-point of metals, the ores used, the need to use fluxes or cope with slag, whether reduction or oxidization took place, and whether the process produced a liquid metal (copper, bronze, gold, a silver–lead mix) to be tapped into moulds to form ingots, or a livid mass (iron bloom) requiring hot hammering. Remelting and refining generally followed; so, ‘work-lead’, remelted under blown air produced metallic silver (for minting coins) and lead-oxide, which again remelted produced lead (for sealing cramps in masonry etc. ). The Greeks used crucible and cupellation methods, developed an early knowledge of alloys (e.g. copper, then arsenical coppers, true copper–tin bronzes, and lead-bronzes for casting), and mastered various hot and cold treatments for metals, smithing, and soldering. Some vase-paintings usefully illustrate workshop activities, like smithing and casting of bronze statues. See mines and mining, Greek.