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(Song Dynasty *Kaibao Bencao* Record)

[Names] Taiyin Xuanjing Shi (Black Crystal of Supreme Yin), Yinjing Shi (Yin Essence Stone, from *Bencao Gangmu*), Xuanying Shi.
Li Shizhen said: This stone is formed by the condensation of the supreme yin essence in alkaline and saline lands; hence these names.

[Collection and Explanation] Su Song said: Xuanjing Shi is produced in Jiechi, Jiezhou. It is also found in the salt warehouses of Tongzhou and Taizhou. Those that are greenish-white with patterns resembling turtle shells are of superior quality. They can be collected at any time. Additionally, there is a Salt Essence Stone in Jiechi which tastes even more salty and bitter; it also belongs to the category of Xuanjing.
Gong said: It is also found in nearby areas, with a greenish-white color, but the pieces are not large.
Li Shizhen said: Xuanjing Shi is formed when alkaline brine seeps into the soil and condenses over many years into stone flakes, shaped like a turtle shell. Those from Puzhou and Jiezhou are transparent greenish-white. Those formed from the liquid of red salt in Shu have a slightly reddish hue. Shen Kuo in *Bitan* stated: Taiyin Xuanjing grows in the great saltpans of Jiezhou salt marshes and is found in the soil of ditches. The large ones are like apricot leaves, the small ones like fish scales; all are hexagonal, regular as if carved, exactly like turtle shells. Their skirts are small and oval; the front tapers downward, and the rear tapers upward, just like the overlapping parts of pangolin scales. It is entirely like a turtle shell, with no difference. The color is green and crystal clear; when struck, it splits along the grain, bright as a mirror. The split surfaces are also hexagonal, about the size of willow leaves. After burning, it splits completely, thin as willow leaves, separating layer by layer, white as frost and snow, flat, clean, and lovely. This is because it inherited the condensed qi of accumulated yin, thus appearing hexagonal. What is currently used as Xuanjing Shi throughout the world is actually Jiangshi (Jiang Stone) from the mountains of Jiangzhou, not true Xuanjing Shi.

[Flavor and Properties] Salty, warm, non-toxic.
Li Shizhen said: Sweet, salty, cold.
Dugu Tao said: It can moderate the properties of Realgar (Cinnabar) and Sulfur.

[Indications] Dispels wind-cold pathogenic factors and damp-bi obstruction; benefits essence and qi; treats chronic cold-induced leukorrhea in women; treats accumulation of cold qi in the heart and abdomen; stops headache; releases the muscle layer (*Kaibao Bencao*).
Treats Yin-pattern Shanghan (Cold Damage); cyanosis of fingernails and complexion; fullness, distension, and hardness below the heart; irritability and thirst; unremitting deficiency sweating; occasional delirious speech; cold reversal of the four limbs; throat discomfort, swelling, and pain; pulse that is deep, fine, and rapid. It should be taken combined with other herbs. Also, when combined with other herbs, applied topically to treat severe wind sores (Cheng).

[Elucidation] Su Song said: It was not used in ancient formulas; in recent times, it is often used in tonics and for treating Shanghan. A famous application is the Zhengyang Dan for inducing sweating in Shanghan.
Li Shizhen said: Xuanjing Shi inherits the essence of Taiyin (Supreme Yin). Its nature is similar to salt; its qi is cold rather than warm, and its flavor is sweet and salty with a descending action. Combined with Sulfur and Niter, it treats excess above and deficiency below, rescues yin and assists yang, and has the merit of supporting critical conditions and reversing adverse trends. Therefore, Mr. Shen Tie-weng uses it in Laifu Dan, precisely taking advantage of its cold nature to balance the heat of Niter and Sulfur. The statement in *Kaibao Bencao* that it is warm is erroneous.

[Attached Prescriptions] One old prescription, eight new prescriptions.
Zhengyang Dan: Treats three days of Shanghan, characterized by headache, high fever, and dysfunction of the four limbs. Taiyin Xuanjing Shi, Niter, and Sulfur, each 2 liang; Cinnabar 1 liang. Grind finely, place in a porcelain bottle, and seal tightly. Calcine with half a jin of fire, covered with one cun of material, for approximately half a day, until the medicine turns blue-purple, then stop heating. Wait for it to cool, take out, mix evenly with snow water collected in the twelfth lunar month, place in a jar, and dry in the shade under the north side of the house. Then bury it in the ground for twenty-seven days, take out, grind finely, and bind with wheat paste to make pills the size of corn kernels. First, take a hot bath, then dissolve one pill in Mugwort Decoction and swallow. Cover with clothes to induce sweating for recovery (*Tujing Bencao*).
Pediatric Wind-Heat, harboring wind and accumulating heat, body heat: Taiyin Xuanjing Shi 1 liang, Gypsum Fibrosum 7 qian 5 fen, Borneolum Syntheticum 0.5 liang. Grind into powder. Take 0.5 qian per dose, washed down with fresh well water (*Puji Fang*).
Lung Heat Cough: See prescription under Ash Wood (*Buhui Mu*).
Cold-Heat Huoluan (Vomiting and Diarrhea), differentiating and benefiting yin and yang: Xuanjing Shi and Pinellia Tuber, each 1 liang; Sulfur 3 qian. Grind into powder, bind with wheat paste to make pills the size of mustard seeds. Take 30 pills per dose with rice drink (*Zhinan Fang*).
Head Wind and Brain Pain: Powder of Xuanjing Shi, placed inside sheep gallbladder and dried in the shade. Mix with water to the amount of "one character" (approx. 1-2 grams), blow into the nose; pain stops immediately (*Qianjin Fang*).
Red Eyes with Dryness and Pain: Xuanjing Shi 0.5 liang; Phellodendron Bark (processed) 1 liang. Grind into powder. Apply to eyes; effective (*Puji Fang*).
Red Eyes Leading to Blindness, Internal and External Opacities: Taiyin Xuanjing Shi (processed by yin-yang fire) and Haliotidis Concha, each 1 liang; Descurainiae Semen and Coptidis Rhizoma, each 2 liang; seven Sheep Livers (cut and sun-dried with bamboo knife). Grind into powder, bind with millet rice porridge to make pills the size of mustard seeds. Take 20 pills with tea before sleep. After seven days of medication, cauterize the vertex of the head to assist the medicinal power; results seen within one month. Prime Minister Song stated: Official Huang Dian-shi suffered from this disease and dreamed of a deity transmitting this prescription, which cured him (*Zhu's Collected Effective Prescriptions*).
Red Veins Growing in Eyes: Xuanjing Shi 1 liang; Licorice Root 0.5 liang. Grind into powder. Take 1 qian per dose, 0.5 qian for children, mixed with Bamboo Leaf Decoction (*Zongwei Lun*). Red Tongue with Saliva Flow, inability to swallow fluids: Taiyin Xuanjing Shi 2 liang; Bovaris Calculus, Cinnabar, and Borneolum Syntheticum, each 1 fen. Grind into powder. Use a lancet to prick the tongue and remove blood, rinse mouth with salt water, sprinkle powder and swallow saliva; miraculous effect (*Shenghui Fang*).