Rock Characteristic And Formation Of Qingtian And Changhua Stone

Colored stones, a kind of nature materails, are beautiful and delicate, and suitable for processing artifacts and ornaments. The foursome—Qingtain Stone, Changhua Stone, Balin Stone and Shoushan Stone—is earned the honor of being designated famous and important seal stones in Chinese traditional stone culture. Geologically, they are comprised of clay minerals, formed by hydrothermal metasomatism and metamorphism and a kind of secondary quartzite. According to field investigation and previous research results, this papers are focused on petrographical observation, spectrum analysis—X-ray diffraction analysis, scanning electron microscope analysis, infrared spectroscopic analysis and differential thermal analysis, analysis of whole rock chemical composition, Ree and race elements, and radioactive isotope geochemistry analysis, suggesting that hydrothermal metasomatism and metamorphism of intermediate-acid volcanic rocks lead to the formation of Qingtian Stone and Changua Stone.Our research shows that texture and structure of Qingtian Stone and Changhua Stone (palimpsest, crystalloblastic and cryptocrystalline texture) is a reflection of their metasomatic alteration intensity. Qingtian Stone and Changhua Stone are mainly comprised of clay minerals, which are pyrophyllite, dickite, kaolinite, transitional mineral of kaolinite and dickite, and illite, and so on. According to components of protolith and metamorphic conditions, several crystalloblastic minerals (such as corundum and andalusite) come into being, which are one of the most important factors that determine the appearance of colorful pattern or not. We explored and analyzed whole rock chemical composition, REEs, race elements and radioactive isotope of Qingtian Stone and Changhua Stone, argued that they are a kind of low-grade metamorphic rocks and formed by hydrothermal metasomatism and metamorphism of intermediate-acid volcanic rocks. Finally, we suggested new definition and classification of Qingtian Stone and Changhua Stone, improved their quality assessment, and proposed six quality rating class.