Gemmological Characteristic of Fracture in Tianhuang

Tianhuang is the most precious variety of Shoushan stone, one of the four famous stones in China. It has profound cultural connotation and attracts much attention to jewelry and collectibles markets. The fracture, rough stone crust and radish fiber like veins are the typical identification characteristics of Tianhuang. The fracture is the visible reddish-brown healed fissure in Tianhuang and its systematic study has important theoretical value for the scientific identification of Tianhuang. The microscopic observation, scanning electron microscope, energy dispersive spectrometer and Raman spectrometer were used to study the micromorphological and compositional characteristics of the fracture in Tianhuang. The results suggested that the fracture in Tianhuang is due to external forces and the Fe element seeps into the fracture caused by primary deposit of Tianhuang and forms goethite in the secondary acidic oxidizing environment, which causes the reddish-brown colour of the fracture. The Raman peaks at 252 cm^-1 and 384 cm^-1 have great significance for the identification of natural fracture in Tianhuang.