Metamorphic graphite deposit, with stratiform and lenticular orebodies hosted in a series of mudstone-dolomitic limestone of the Paleoproterozoic Dapandao Formation. Their original sedimentary environment is interpreted as littoral plain-tide flat-lagoon system. The series underwent regional metamorphism of granulite-amphibolite facies.

The ore-bearing strata in the YGD are primarily hosted in the Dapandao Formation of the Xingdong Group. The rock types of the ore body within the YGD progressively transition from northwest to southeast, in the sequence of graphite-mica schist, graphite-quartz schist, and graphite-plagioclase gneiss, among which the graphite-quartz schist serves as the principal ore-bearing lithology. The surrounding rocks at the top and bottom of the ore body in the YGD are mainly marble, biotite-quartz schist, and mixed granite. The ore-endowed layer is about 2900 m long and 2300 m wide, in the form of a thick layer, and the occurrence of the ore body is consistent with the occurrence of the strata, characterized by convergence to the north and divergence to the south. The ore bodies are distributed in strips inclined to the east, with dips ranging from 25° to 55°. The local minimum inclination is only 5°, and the maximum inclination can reach 60°. The ore bodies exhibit a compact distribution pattern that the surface parts of the ore bodies are steeper, and the deeper parts gradually become slower. The average content of graphite in the ore bodies is between 15 wt% and 25 wt%, up to 45 wt%. The proven industrial ore reserves in the YGD amount to 264.3839 million tons, making it the largest crystalline graphite deposit in China. A potential three-stage model involving deposition, metamorphism, and retrograde metamorphism is proposed to be responsible for the formation of variably crystalline graphitic carbons in the YGD.

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