Acta Petrologica et Mineralogica

Purple "Shanzilai stone", a kind of Shoushan stone, is a layered silicate mineral clay jade. Its surface weathering for yellow, interior purple, corresponds to the seal stone in the rather unusual color variants. A standard gemstone microscope was used to examine the visual attributes. X-ray powder crystal diffractometer, microscopic laser Raman spectrometer, scanning electron microscope, and laser denudation plasma mass spectrometer were used to investigate the mineral composition, chemical composition, and rare earth elements (REE). The cause of the color was investigated using whole-rock chemical analysis, UV-visible spectrophotometer, and SPSS analytical model. According to the findings, the principal mineral composition of the purple "Shanzilai stone" is illite, with minor minerals including monazite, gorceixite, hematite and barite. The REE indicator data demonstrate an enrich of LREE components and a deficiency of HREE, indicating that the minerals' origin is associated to less acidic hydrothermal alteration. Illite’s purple hues and manganese concentration have a favorable association. The different types, distribution characteristics, and formation temperatures of the main minerals and secondary minerals in purple "Shanzilai stone" indicate that hydrothermal intrusion occurred several times during the late mineralization period, and the purple "Shanzilai stone" formation process is consistent with the metallogenic law in the Shoushan area.

purple "Shanzilai stone"; illite; scanning electron microscope; Raman spectroscopy; metallogenic mechanism