The Xinlantian jade deposit mined today is located in the Yuchuan and Hongxing areas of Lantian County, Shaanxi Province, about 35 kilometers away from the county seat. The ore-bearing rock layers are Archean biotite schist, hornblende gneiss, etc. Jade is a fine-grained marble composed mainly of calcite. Jade can be divided into five types according to its mineral composition and appearance characteristics: the first is white marble. The second type is light beige serpentine marble. The third type is yellow serpentine marble. The fourth type is apple-colored serpentine marble. The fifth type is striped tremolized serpentine marble. Lantian jade is a famous jade in ancient times. As early as the Qin Dynasty, it was quarried to make jade seals, including the famous Heshi Bi. There are records of the beautiful jade produced in Lantian in many ancient books from the Tang Dynasty and before. According to records, Emperor Ming of the Tang Dynasty ordered people to collect Lantian jade to make a percussion instrument for Concubine Yang Guifei. His "Hanshu Geography" states that beautiful jade comes from "Lantian Mountain in the north of Beijing (now north of Xi'an)". Later, ancient books such as "Book of the Later Han Dynasty: Biography of Foreign Relations", Zhang Heng's "Ode to Xijing", "Guangya", "Shui Jing Zhu" and "Yuanhe County Map" all have records of jade produced in Lantian. During the Wanli period of the Ming Dynasty, Song Yingxing said in "Tiangong Kaiwu": "The so-called Lantian is another name for the jade produced in Congling (Kunlun Mountain), and was later mistakenly thought to be Lantian in Xi'an.
”