Silver

Silver reached the alchemical workshop chiefly as a byproduct of lead smelting, extracted from silver-bearing galena ore by cupellation, the process of oxidizing away the lead under an air blast while the more chemically resistant silver remained behind as a pure metallic bead, a technique practiced at real scale across the ancient and medieval world and responsible for most of the silver coinage of those periods. Pure silver is bright white, highly reflective and more malleable than most metals besides gold, properties that made it prized for coinage, tableware and mirror backing alike, though unlike gold it slowly tarnishes, developing a dark grey to black surface film where trace hydrogen sulfide or other sulfur compounds in ordinary air react with the metal's surface, a familiar nuisance to anyone who has owned silver jewelry or tableware.

Alchemically, silver's brightness and its association with reflected rather than self generated light, exactly as the Moon reflects the Sun's light rather than producing its own, made the Moon correspondence feel intuitively apt to writers across the tradition, and silver was regularly discussed as gold's closest relative among the seven metals, second in the hierarchy of perfection and sometimes treated as a substance one step away from achieving gold's own stability. Amalgamated with mercury, silver formed one of the standard alchemical amalgams, used in gilding and mirror-making techniques covered separately in this atlas.

Silver's pairing with the Moon is, like gold's pairing with the Sun, one of the oldest and most consistently attested correspondences in the alchemical tradition, appearing across Hellenistic, Islamic and European sources with no significant historical dissent recorded by historians such as Lawrence Principe. Its alchemical symbol, a simple crescent, is identical to the Moon's own astrological glyph, again a direct visual expression of the correspondence rather than an arbitrary assignment.

Silver's slow tarnishing, in contrast to gold's near total resistance to it, gave alchemical writers a ready made explanation for why silver ranked second rather than first in the metallic hierarchy: it was closer to perfection than lead, tin, copper or iron, but not yet as stable, as fully matured, as gold itself, a graded scheme of relative perfection that modern chemistry does not recognize in those terms but that gave the alchemical tradition a coherent, internally consistent account of why the seven metals differed as they plainly did in their resistance to corrosion. Silver's continued role as a store of value alongside gold, in coinage and bullion alike, long after alchemical metallic hierarchies stopped guiding serious chemistry, shows how durable a practical, economic ranking of the metals proved even once its original theoretical justification fell away.