Geochemical Characteristics of Nephrite from Chuncheon, South Korea: Implications for Geographic Origin Determination of Nephrite from Dolomite-Related Deposits

The Chuncheon nephrite deposit in South Korea is one of the major nephrite deposits in the world, but its origin has been rarely studied. This study explores the mineralogical and geochemical characteristics of the Chuncheon nephrite using a polarizing microscope, an electron microprobe, laser ablation, inductively coupled plasma mass spectrometry, and hydrogen-oxygen isotope analyses and compares them with dolomite-related nephrite worldwide. The main mineral of Chuncheon nephrite is tremolite, which has a felted blastic texture, secondary filling texture, and metasomatic pseudomorphic texture that nephrites from other regions do not have. Chuncheon nephrite is dolomite-related; the total content of rare earth elements is generally low, with highly variable positive and negative Eu anomalies and weak positive Ce anomalies; and the light rare earth elements are enriched. The Chuncheon nephrite formed in an anaerobic alkaline environment with a low degree of mineralization, and the hydrothermal fluids are predominantly meteoric water. Nephrite from different regions has different geochemical characteristics as well as different abundances of rare earth element contents. According to the content and range of elements, such as delta Ce, delta Eu, sigma REE, (La/Sm)N, and other rare earth elements, dolomite-type nephrite from different origins can be roughly distinguished.