Geological Characteristics and Genetic Analysis of Diopside–Tremolite Deposit in Laozhuang, Nanzhao County, Henan Province

Laozhuang diopside–tremolite deposit in Nanzhao county is the only diopside–tremolite deposit in Henan Province. The mining area is located in the north of Luanchuan–Minggang regional fault, and the tectonic position is in the south margin of North China block. There are two diopside–tremolit eorebodies in the mining area, which occur in the upper part of Nannihu formation of Luanchuan group of Qingbaikou system in stratoid form. The orebody morphology is simple. The wall rock alteration are mainly tremolite and diopside, followed by potassic feldspar and phlogopitization. The natural types of ores are mainly phlogopite diopside skarn, phlogopite diopside skarn and phlogopite diopsides karn. The mineral composition is mainly tremolite and diopside, followed by potash feldspar and phlogopite, a small amount of calcite. The chemical composition of the ore are SiO₂, CaO, MgO and Al₂O₃, followed by FeO, K₂O, Na₂O and CO₂. Ore grade: tremolite + diopside (Tl + Di) is relatively high and stable, and the average ore grade (Tl + Di) is 68.25%. The preliminary test of diopside raw ore replacing wollastonite in the production of glazed tile shows that the product has stable performance and obvious energy saving effect. The deposit belongs to skarn type and the metallogenic epoch is early Cretaceous. The formation of the deposit is controlled by early Cretaceous Zhuyuan quartz syenite porphyry, dolomite marble in the upper Nannihu formation and interlayer fracture zone. Skarn stage is the main metallogenic stage. Diopside is formed in dry skarn stage, tremolite is formed in wet skarn stage, and potash feldspar, phlogopite and calcite are formed in oxidation stage.