Langgan 琅玕 is the ancient Chinese name of a gemstone which remains an enigma in the history of mineralogy; it has been identified, variously, as blue-green malachite, blue coral, white coral, whitish chalcedony, red spinel, and red jade. It is also the name of a mythological langgan tree of immortality found in the western paradise of Kunlun Mountain, and the name of the classic waidan alchemical elixir of immortality langgan huadan 琅玕華丹 "Elixir Efflorescence of Langgan". Word The Chinese characters 琅 and 玕 used to write the gemstone name lánggān are classified as radical-phonetic characters that combine the semantically significant "jade radical" 玉 or 王 (commonly used to write names of jades or gemstones) and phonetic elements hinting at pronunciation. Láng 琅 combines the "jade radical" with liáng 良 "good; fine" (interpreted to denote "fine jade") and gān 玕 combines it with the phonetic gān 干 "stem; trunk". The Chinese word yù 玉 is usually translated as "jade" but in some contexts translates as "fine ornamental stone; gemstone; precious stone", and can refer to a variety of rocks that carve and polish well, including jadeite, nephrite, agalmatolite, bowenite, and serpentine. Modern written Chinese láng 琅 and gān 玕 have variant Chinese characters. Láng 琅 is occasionally transcribed as láng 瑯 (with láng 郞 "gentleman") or lán 瓓 (lán 闌 "railing"); and gān 玕 is rarely written as gān 玵 (with a gān 甘 "sweet" phonetic). Guwen "ancient script" variants were láng 𤨜 or 𤦴 and gān 𤥚. Berthold Laufer proposed that langgan was an onomatopoetic word "descriptive of the sound yielded by the sonorous stone when struck". Lang occurs in several imitative words meaning "tinkling of jade pendants/ornaments": lángláng 琅琅 "tinkling/jingling sound", língláng 玲琅 "tinkling/jangling of jade", línláng 琳琅 "beautiful jade; sound of jade", and lángdāng 琅璫 "tinkling sound". Laufer further suggests this etymology would explain the transference of the name langgan from a stone to a coral; Du Wan's 杜綰 c. 1125 Yunlin shipu 雲林石譜 "Stone Catalogue of the Cloudy Forest" (below) expressly states that the coral langgan "when struck develops resonant properties". Classical descriptions The name langgan has undergone remarkable semantic change. The first references to langgan are found in Chinese classics from the Warring States period (475-221 BCE) and Han dynasty (206 BCE-220 CE), which describe it as a valuable gemstone and mineral drug, as well as the mythological fruit of the langgan tree of immortality on