Pronounced hu (falling tone). According to "Guangyun," the pronunciation is indicated by the rhyme group "hu wu" (胡误). According to "Jiyun," it is indicated by "hu gu" (胡故). "Yuepian" states it is a blue mineral. "Jiyun" states it is a black mineral. "Shanhaijing" records: On Qingqiu Mountain, to the south of the mountain there are many jades, and to the north of the mountain there are many qingdu (青䨼). The commentary states: Du (䨼) is pronounced "hu" and refers to a black mineral. "Shangshu Dazhuan" states: Qingqiu produces qingdu (青䨼), which are currently materials like stone blue and white blue. "Liushu Suoyin" states: A good red is called "luo" (雘), with a character structure derived from "dan" (丹). A good blue is called "du" (䨼), with a character structure derived from "qing" (青). Note: "Yuepian" states that "qingdu" (青䨼) is the name of a mountain, which is incorrect.