ZnS has high theoretical capacity (962.3 mAh·g−1) and low discharge platform. However, it has poor electrical conductivity and cycling performance for lithium-ion batteries (LIBs). In this study, a natural mineral of ZnS doped with iron called marmatite was discovered. Results indicated that this natural marmatite has a structure similar to that of the ZnS of the Td2-F4-3m space group and also has low discharge platform (<1 V). Compared with pristine, the natural marmatite has superior electrochemical stability (After 1000 cycles at a current density of 2000 mA g−1, a capacity of 651 mAh·g−1 with a reversible capacity retention rate of 94% remained.) and higher capacity (1009 mAh·g−1 at a current density of 200 mA g−1). These results indicated that the natural marmatite exhibits high capacity and excellent cycle performance, demonstrating unique potential for next-generation LIBs.