The discovery of beryllium mineralization at the Tongshanyuan copper polymetallic deposit, Zhejiang Province, South China, and its geological significance

The Tongshanyuan copper polymetallic deposit is located between the two faults of Jiangshan-Shaoxing and Lishui-Yuyao, Lishui-Ningbo Uplift Zone belong to southeastern Zhejiang Fold Belt of the Cathaysia Fold System. The mineralization of this deposit is mainly controlled by northeast-trending and northwest-trending compression faults, and the host rock is the Zhantou Formation of the Proterozoic Badu Group. The mineralization is mainly divided into fractured-zone altered rock type and quartz vein type, respectively. On the basis of systematic geological investigation and the chemical analysis , we found significant enrichment of beryllium in the fractured-zone altered rock type ores, with Be content ranging from 15.5x10(-6) to 147x10(-6) . Based on the EPMA and Laser Raman Spectroscopy analysis, the beryllium mineral is mainly composed of bertrandite. The fluoritization and carbonation is closely related to bertrandite precipitation, which can be classified as a new type of beryllium mineralization-metamorphic-modified beryllium ores. In this type of deposit, Be may mainly migrated in the form of (BeF (4))(2-) and [Be(CO3)(2)](2-) complexes in the ore-forming fluid . When the ore-forming fluid encounters Ca-bearing minerals such as andradite, F- or CO32- in the hydrothermal solution combines with calcium iron to form fluorite or calcite, causing (BeF4)(2-) and [Be(CO3)(2)] (2-) complexes to precipitate in the form of bertrandite. The discovery of beryllium mineralization at the Tongshanyuan copper polymetallic deposit provides a good example for searching for this new beryllium resources in the area. The paper also suggests much more attention should also be paid to the enrichment and mineralization of other key metals such as Cd, Co, and In in the area when searching for this new type beryllium resources.