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Toxic.
Tuhuang (Earth Yellow) treats withered tumors, warts, hemorrhoids, breast diseases, and food stagnation, as well as various sores with foul flesh (Compendium of Materia Medica). [Flavor] Acrid, sour. [Nature] Hot. [Processing] (Li Shizhen states) Take 2 liang of Pishishi (Arsenic Stone), half a liang each of Muguezi Ren (Seed of Momordica charantia) and Badou Ren (Seed of Croton tiglium), and 2 qian of Sha (Sand), grind into fine powder, mix with Muguezi You (Oil from Seed of Momordica charantia) and Shinao You (Naphtha oil) to form a paste, wrap in oil paper, bury in an earth pit for 49 days, take out, split into small pieces, and store in porcelain vessels. [Explanation] (Dugu Tao states) Tuhuang is the processed form of Xionghuang (Realgar).

Jingangshi (Diamond) treats water ground from it applied to scalds and burns, or worn as a hairpin to ward off evil and toxic vapors (Compendium of Materia Medica). [Names] Jingangzuan (Diamond Drill), Xiaoyudao (Jade-Cutting Knife) (Li Shizhen states) Its sand can drill jade and repair porcelain, hence called "Zuan" (Drill). [Origin] (Li Shizhen states) Produced in Xifan (Western Regions), Tianzhu (India), etc. (Ge Hong's *Baopuzi* states) Funan produces Jiangangshi, which grows on stones at the bottom of water. (Zhou Mi's *Qidong Yeyu* states) It is said to be produced in high mountains of the Western Regions and Uyghur lands; eagles carry it, swallow it, and excrete it in the sandy deserts north of the Hebei River; whether this is true is unknown. (*Yuan Zhong Ji* states) Daqin (Rome) produces Jiangang, also known as Xiaoyudao; large ones are about one chi long, small ones like rice grains, can be threaded through rings to carve jade. From this, we see that there are very large diamonds; Tibetan monks use them as Buddha teeth. (*Shizhou Ji*) records Kunwu stone in the flowing sands of the West Sea; when processed into swords, they are bright as iron and crystal clear, cutting jade like mud; these are also extremely large diamonds. There are beasts such as Mo (Tapir) and Jiaotu (Iron-biting Hare) that can eat iron, and their feces can be used to make weapons. See details on carving jade under the entry for Mo in the Beast section. [Harvesting Time] (Harvested) in summer and autumn, when the weather is hot, people can dive into the water to collect it. [Usage] Can carve jade (Zhou Mi's *Qidong Yeyu* states) Jade workers process jade using Ganges sand combined with a diamond drill. [Texture] Shape resembles Zhongru (Stalactite), body similar to Zishiyingshi (Purple Quartz), also resembling rat droppings. [Color] Bluish-black, like stone or iron. [Nature] Extremely hard; even if struck by an iron hammer, it cannot be damaged. [Processing] If it feels dull, heat it until red, then cool it to set, and it will become sharp again. [Contraindications] (Ge Hong's *Baopuzi* states) If struck by Lingyangjiao (Antelope Horn), it melts away like ice. (*Danfang Jianyuan* states) ZiBei Qian (Lead with Purple Back) can crush diamond drills. [Adulterant Identification] To distinguish authenticity, heat it until red, quench it in vinegar; if it remains intact and does not crumble, it is genuine. ○ (*Yuan Zhong Ji* states) Diamond is the hardest, yet Antelope Horn can overcome it; thus one can understand that desires are sufficient to confuse truth. Therefore, in the West, Diamond is used to metaphorize Buddha-nature, and Antelope Horn to metaphorize afflictions.