| Larderite, also known as “Shoushan Stone” in China, is named after Shoushan, a mountain located in Fujian Province, where most larderites are mined. Belonging to the category of jade rocks and mainly consisting of clay minerals, larderite can be used to make art engravings and seal cutting stamps. Based on field geological investigation, naked eye observation, micropolariscope observation, Scanning Electron Microscope (SEM), Electron Probe Microanalysis (EPMA), X-ray Diffraction (XRD) analysis, Infrared Spectroscopy analysis and DSC technology, the authors studied the types and characteristics of larderite in Shoushan area of Fujian Province as well as its primary mineral composition, microstructure, and crystal texture. According to the component analysis of larderite deposits of Gaoshan, Qijiang, Emei and Yuewei, there are four main types of larderite deposits (primary ore), i.e., dickite, kaolinite, pyrophyllite, and illite. The main textures of larderite are microaphanitic, microaphanitic-microcrystallite, and microcrystallite structure. Gaoshan stone is made of pure and ordered dickite. Emei stone is made of pure 2M type pyrophyllite, while some of Yuewei stones are made of 2M1 type illite. Qijiang stone mainly consists of ordered kaolin, which contains a few kaolin-dickite intergradient minerals. Some of Qijiang stones are made of 2M type pyrophyllite, which contains a few kaolin minerals. Based on the feature analysis of geological occurrence of mineral deposits, ore textures and mineral assemblages, the authors hold that larderite was formed through hydrothermal alteration in a reducing metallogenic environment. |