Sal ammoniac

Sal ammoniac

　　Li Shizhen said: "Sal ammoniac is toxic and can cause mental confusion, hence its name 'brain sand'." Sal ammoniac is a mineral of the halide class, either purple rock salt or a type of ammonium chloride ore. It comes in two varieties, purple and white. The purple one is called purple sal ammoniac, known in Tibetan as "karuca."

　　The white one is called white sal ammoniac, known in Tibetan as "jianmuchu." Purple sal ammoniac belongs to the axial crystal system, with varying color and density, soluble in water, and recrystallizes into cubic halite; white sal ammoniac belongs to the isometric crystal system, with large grains, forming octahedral or cubic intergrowths that aggregate into columnar or fibrous structures, or appear granular in precise aggregates. When dissolved in water, it recrystallizes into arrow-like acicular skeletal crystals. Sal ammoniac is mainly found in the Qaidam Basin. It has effects such as resolving accumulation, softening hardness, breaking up blood stasis, dispersing nodules, expelling phlegm, and removing nebula. It is used for treating abdominal masses, food stagnation, choking sensation, vomiting, phlegm-fluid retention and throat bi, accumulated dysentery and amenorrhea, as well as externally for eye nebula, warts, swelling pain, and malignant sores.