Pore Structure and Fractal Dimension Analysis of Nephrite Deposits in Luanchuan, Western Henan, Central China

Pore structure and fractal dimension analysis of nephrite deposits are essential for assessing potential quality, conducting investigations, and exploiting jade resources. This research explored nephrite (tremolite) jade from Tonggou in the Luanchuan Group, utilizing techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and low-temperature nitrogen adsorption (LT-N2GA) to illustrate the pore structure of the jade deposit and to examine its developmental features, complexity, and implications for jade quality assessment. The findings revealed that the Tonggou nephrite jade deposit comprises three varieties of micropores. The nitrogen adsorption curve was similar to type IV, featuring hysteresis loops that were mainly classified as H2 and H3, suggesting a predominantly mesoporous nature. The fractal dimensions (DF1 and DF2), determined using the FHH model, averaged 2.474 and 2.572, respectively. This implies that the pore surface of the Tonggou jade deposit is irregular, the pore structure is intricate, and displays a pronounced heterogeneity. In the Tonggou deposit, the specific surface area (SSA) and pore volume (PV) show moderate positive and negative correlations with antigorite and calcite, respectively. Tremolite exhibits a strong negative correlation with SSA. The fractal dimension reveals weak, moderate, and strong negative correlations with SSA, PV, and average pore size (APS), respectively. As the content of siliceous minerals increases, the fractal dimension gradually increases. Conversely, a rise in carbonate mineral content results in a gradual decrease in the fractal dimension.