Alum (Colorless and transparent, crystalline lumps, lustrous, smooth longitudinal ridges on the surface, attached with white powder, brittle, sour and astringent)
【Naming】
【Source】
Superior Grade in the Classic of Herbal Medicine
【Common Usage Level】
D
【Botanical Origin】
Crystalline substance refined and extracted from alunite, a sulfate mineral.
【Characteristics】
Colorless, transparent, hard octahedral crystals or crystalline lumps, with luster. The surface is covered with white powder, brittle, with a hardness of 3.5~4; specific gravity of 2.6~2.8. It has an astringent taste; the powder is white.
Calcined alum is snow-white, opaque, light and spongy, with a rough surface and irregular lumps with powdery properties.
【Processing】
1. Used raw 2. Calcination method for calcined alum
【Identification】
《Secret Essentials from the Imperial Library》: “Alum that is burned to resemble a horse’s tooth is considered good.” 《Formulas for Universal Relief》: “Copper sulfate is best when it comes from Xinzhou or Puzhou, is bright like emerald glass, and resembles a duck’s beak.” 《Classified Collection of Medical Formulas》: “Alum that is refined to a white color is considered good.” 《Compendium of Materia Medica》: “Alum with textures like bundled needles, resembling face powder, is Persian white alum, and is good for medicinal use,” “Persia also produces gold-threaded alum; the superior kind has gold thread patterns when broken open.” 《Further Investigations of Herbal Signs》: “One type grows naturally, like willow catkins, called willow catkin alum, which is the highest grade.” 《Seeking Truth from Materia Medica》: “It is best to choose those that are clean, white, and lustrous.” 《Discrimination of Good and Bad》: “The superior kind does not have a white powder frost and forms large, transparent crystals.”
It is best to use colorless and transparent pieces that do not contain rock fragments.
【Category】
Minerals