Black Nephrite’s Characteristics And Preliminary Study Of Graphite’s Influence On Its Quality

In this paper, which target at the phenomenon that people usually cannot distinguish between the real and the fake black jade in the gem markets especially in tourist, through the market survey and the laboratory test, method of gemology and mineralogy has been used to confirm the mineral composition characteristics. Black Xiu Yu and Black Ka Wa(a business name), Both of which do not belong to the category of black nephrite. In summary, black nephrite have different mineral composition, can be divided into the following four categories.There are two kinds of mineral composition form about Hei Bi jade(a business name):(1)The tremolite rock containing graphite is composed of tremolite, graphite, metal;(2)The graphite-containing tremolite actinolite rock is composed of tremolite, actinolite, graphite, metal.There are four kinds of mineral composition form about Hei Qi jade(a business name):(1)The tremolite- actinolite rock is composed of tremolite, actinolite, metal;(2)The actinolite rock is composed of tremolite, metal;(3)The hornblende rock is composed of hornblende, metal;(4)The hornblende- actinolite rock is composed of actinolite, hornblende, metal.Yan Qing jade(a business name) is the tremolite rock, composed of tremolite, consisting of metal.Black Nephrite jade(a business name) is the graphite-containing tremolite rock, which composed of tremolite, graphite, metal.The graphite in crystalline form into Nephrite jade and results in great hardness and low hardness coexisting. The negative effect of quality of jade on gloss, mohshardness, toughness is as for the structure of graphite. Graphite crystal form and flake size is the main reason for chipping in jade making process. In high quality of Black Nephrite jade, the graphite have low crystallization degree, it uniform distribution in Nephrite jade as microlic and aphianitic, metallic mineral with small crystals in size and contains little.