Formula: Sb₂S₂O

Species: Sulfides

Colour: Red

Lustre: Adamantine

Hardness: 1 – 1½

Specific Gravity: 4.5 – 4.6

Crystal System: Triclinic

Name: From Greek kermes (from the Persian “qurmizq”, “crimson”), a name (in the older chemistry) for red amorphous antimony trisulphide, often mixed with antimony trioxide.

Type Locality: Neue Hoffnung Gottes Mine, Bräunsdorf, Oberschöna, Mittelsachsen, Saxony, Germany

Kermesite or antimony oxysulfide is also known as red antimony (Sb₂S₂O) . The mineral’s color ranges from cherry red to a dark red to a black. Kermesite is the result of partial oxidation between stibnite (Sb₂S₃) and other antimony oxides such as valentinite (Sb₂O₃) or stibiconite (Sb₃O₆(OH)). Under certain conditions with oxygenated fluids the transformation of all sulfur to oxygen would occur but kermesite occurs when that transformation is halted.

Kermesite is named after a formerly used red dye, kermes (dye), and was so named because of the grainy reddish color the mineral often has. The name dates from 1832. Earlier in English (17th and 18th centuries) certain antimony compounds were called “kermes mineral” for the same reason. Kermesite or red antimony has been used as early as the Old Kingdom’s 6th Dynasty in ancient Egypt (c. 2345–2181 BCE) in lip cosmetics and in the 18th Dynasty Queen Hatshepsut (Maatkare) (1498–1483 BCE) negotiated with the Land of Punt for its colored antimony deposits. Besides stibnite, which was used for eye liner red, antimony is one of the oldest minerals used in cosmetics. Further archaeological evidence indicates that antimony levels were higher in ancient Egyptian female remains which had exposure to both antimony compounds. Because of its color, the precipitate of kermesite was used as a coloring agent and in alchemy. Because of alchemy’s focus on material transformation as evidenced by color, red antimony was used to produce the red state. Kermesite is the mineral state for Kermes mineral which was used extensively in the medical field for centuries. Presently, kermesite is collected for the beauty of its crystal metallic structure and not used in either cosmetics or the medical field any longer due to the toxic effects that it shares with antimony; less harmful substitutes have been found using both organic and pharmaceutical production.