Abstract:Ilvaite is a common mineral in skarn-type Pb-Zn deposits and Fe deposits, and is closely related to lead-zinc ore bodies and magnetite ore bodies. In order to find out the relationship between the ore-forming process of ilvaite and Pb-Zn-Fe-Cu polymetallic mineralization, this paper investigated the production environment, mineral symbiotic assemblage, chemical chemistry of ilvaite in the Jinchanghe Fe-Cu-Pb-Zn polymetallic deposit. The composition and zonality were studied. Calculated according to the EMPA data, its chemical formula is: Ca0.95-1.08(Fe0.87-1.97Mn0.08-0.36Mg0.01-0.06)1.89-2.032+(Fe0.82-1.04Al0.01-0.03)0.88-1.153+(Si1.94-2.08O7)O(OH). Combined with the type of mineral assemblage, occurrence, zoning characteristics, etc., it was inferred that the skarn in the deposit will gradually metasomatize from the inner zone to the outer zone. There are mainly 3 mineral symbiotic combinations in Jinchanghe mining area: I、Ilvaite + magnetite combination, II、Ilvaite + magnetite + pyrite + chalcopyrite combination, III、Ilvaite + galena + sphalerite + chalcopyrite combination, corresponds to three different alteration stages: the later skarn stage (representative assemblage I), which is dominated by the decomposition of garnet, forming a large number of ilvaites; the retro-alteration stage(representative assemblage II), mainly actinolite, chalcopyrite, and pyrite developed; at the quartz-sulfide stage (representative assemblage III), ilvaite was further decomposed to form quartz, calcite, magnetite, etc. In addition, the distribution pattern of rare earth elements of ilvaite is very similar to that of garnet, which has certain inheritance. The research believes that the ilvaite is the product of the degradation and decomposition of the early garnet, and the ore deposit is gradually metasomatized from the inside to the outside, forming a Mn-rich ilvaite in the lead-zinc-copper ore body and manganese ilvaite in the magnetite ore body banding feature. Mn-rich ilvaite is conducive to the formation of lead-zinc ore, and has an influence on the depletion of magnetite. Meanwhile, it can also provide important scientific significance for the mining area to expose the neutral acid rock and deep prospecting.