Bronze

Bronze is copper alloyed with tin, and the mixture is harder and easier to cast than either metal alone, which is why it gave its name to an entire span of human history. The Bronze Age runs from roughly 3300 BCE to 1200 BCE depending on the region, marked by the shift from stone tools to cast metal ones, and bronze remained the working metal of choice for tools, weapons and armor until iron smelting spread widely enough to replace it. Because it is a compound rather than one of the seven metals the old planetary system assigned to Sun, Moon and the five visible planets, bronze does not carry a planetary rulership of its own in most esoteric metal tables; its correspondences are usually read through its parents, copper's Venus and tin's Jupiter, blended rather than assigned fresh.

The proportions vary by era and purpose. Early bronzes ran anywhere from five to twenty percent tin, and bell bronze, prized for its ring, uses a higher tin content than tool bronze, which favors toughness over resonance. That practical range is part of why bronze reads, in metallurgical writing going back to Agricola's sixteenth-century De Re Metallica, as a worked craft rather than a single fixed recipe.

Sources De Re MetallicaGeorgius Agricola, translated by Herbert Clark Hoover and Lou Henry Hoover (1912) with The Secrets of AlchemyLawrence M. Principe

Bronze takes a high polish, and polished bronze mirrors were the common scrying surface of the ancient Mediterranean and beyond, long before glass mirrors were practical to make. Greek, Etruscan, Roman and Chinese diviners alike used bronze mirrors both as household objects and as tools of catoptromancy, reading in the reflected or clouded surface. The same reflectivity and durability made bronze the standard metal for temple and votive statuary across many traditions, from Greek votive bronzes to the cast bronze bells that call worshippers to prayer in Buddhist, Christian and Chinese temple practice alike.

Bronze bells in particular carry a ritual weight beyond their material: a cast bell's tone is treated in several traditions as capable of marking sacred time, warding harmful influences, or calling attention across the boundary between ordinary and ritual space, a function tied to the metal's resonance rather than to any single doctrine about what bronze itself means.