Analysis of Jet Structure and Physical Properties in the Coalfields of Northern China

Abstract

Archeological discoveries have identified China as one of the first countries in the world to use jet. However, many differences are evident between the jet currently found in existing mines and the archaeological discoveries of cultural relics in terms of texture and quality according to the definition of organic gem jet in gemology. This paper reports the results of microscopic analysis and coal quality analysis of the coal and jet samples from coal seams in Fushun Open-pit Mine and Datong Coalfield. The findings reveal that the physical and chemical composition of coal in different mining areas differs markedly. However, the differences between jet and coal in both mining areas are similar; that is, jet has lighter density and greater hardness (2–4) compared to coal, as well as elasticity (engravability), and both jet and coal occur in the (rock slurry) hydrothermal environment. Lastly, the analysis shows that the formation of jet depends on rubber-like hydrocarbon coal with a high degree of corruption in a sedimentary environment under the vulcanization of a hydrothermal, high-sulfur environment.