Antimony

Antimony, as ore, is the dark grey, metallic-luster mineral stibnite, mined and ground since antiquity for use as kohl, the dark cosmetic applied around the eyes across the ancient Near East, Egypt and beyond, a use attested for thousands of years before its chemistry was understood at all. Smelting stibnite with iron reduces the sulfide ore, the iron combining with the sulfur and releasing the antimony as a brittle, bluish-white, crystalline metal that alchemists called the regulus, a term also applied to the similarly obtained metallic buttons recovered from other ore reductions. The regulus of antimony was a substance of particular fascination in the seventeenth century, most famously through the writings attributed to Basil Valentine, whose Triumphal Chariot of Antimony treated the metal and its many compounds as unusually powerful medicines and poisons at once, a genuine ambivalence borne out by modern toxicology, which recognizes antimony compounds as both historically used medicinally and genuinely hazardous.

Antimony and its compounds, butter of antimony and powder of algaroth among the most famous, were investigated intensively as purgative medicines through the seventeenth and eighteenth centuries, a use controversial even at the time given how easily an antimony dose could tip from therapeutic to poisonous. The metal's brittleness and its useful property of expanding slightly on solidifying, unusual among metals, made it valuable later for type metal in printing, an application that outlasted its alchemical and medical uses by centuries.

Antimony's ore, stibnite, is identified as antimony trisulfide, Sb2S3, and the smelted metal is identified as elemental antimony, Sb, a metalloid element with chemical behavior intermediate between a true metal and a non-metal, both identifications well supported and essentially uncontested. What remains genuinely unsettled is antimony's place in the classical planetary scheme: unlike the seven metals proper, gold, silver, mercury, copper, iron, tin and lead, each tied by long convention to one of the seven planets, antimony was sometimes treated by alchemical writers as a kind of eighth, ambiguous metal, associated inconsistently with different planets or, in some interpretive traditions, treated as belonging to no single planet at all, a genuine disagreement in the historical sources rather than a gap in modern scholarship. This entry deliberately leaves the planetary attribution unassigned rather than picking one contested claim over another, consistent with how the sources themselves disagree. Basil Valentine's own text repeatedly stresses antimony's dual, contradictory nature, at once a valuable medicine and a genuine poison, a characterization that any single fixed planetary attribution would tend to flatten rather than honor.