Kermes mineral
Kermes mineral or Alkermes mineral was a compound of antimony oxides and sulfides, more specifically, antimony trioxide and trisulfide. It can be made or obtained in the laboratory by the actions of potassium carbonate (K2CO3) on antimony sulfide. The compound is reddish brown in color and described as a velvety powder which is insoluble in water. It was used extensively in the medical field until the general use of antimony compounds declined due to toxic effects.