Mineralizations of Base Metal Deposits of Acid‐Sulfate Type Coexisting with Adularia‐Sericite Type

Abstract

: Two types of ores are recognized in the Huanzala mine, Peru. Zinc and lead ore of adularia‐sericite type, is accompanied by pyrite body and skarn. Orthoclase (adularia), sericite and calcite are found in the skarn and altered country rocks. On the other hand, copper and silver (tin) ore of acid‐sulfate type, is characterized by enargite, luzonite and bornite, accompanied by tin, silver and tellurium minerals. Although sericite and calcite are found only at the earlier stage in the mineralization of acid‐sulfate type, kaolinite appears in the country rocks at a subsequent stage. It is interpreted that the ore‐forming fluid of the acid‐sulfate type separated from the adularia‐sericite type by boiling in the early stage of mineralization. The separated fluid was nearly neutral just after boiling and changed into acidic by the oxidation of H2S into HSO4‐. Both types of mineralizations are studied in terms of fo2‐fs2‐pH‐temperature diagrams. The adularia‐sericite type might correspond to the hot‐water system of a geothermal area, and the acid‐sulfate type to the vapor‐dominated system. The copper ores from the Teine mine, Hokkaido, Japan and the Chinkuashih mine, Taiwan are acid‐sulfate type, characterized by the occurrence of enargite and luzonite. However, zinc and lead ores of the adularia‐sericite type are also present in these deposits. Both types in the Teine and Chinkuashih deposits are supposed to have formed in the similar relation as in the Huanzala deposits. The enargite and luzonite ores in the Hokuetsu mine, Japan are closely associated with native sulfur of solfataric origin.

Evidence for syngenetic micro-inclusions of As3+- and As5+-containing Cu sulfides in hydrothermal pyrite

“…The association of pyrite with Cu-bearing minerals, such as enargite, colusite, Asgoldfieldite and mawsonite, is common in high-sulfidation deposits (e.g., Mancano and Campbell 1995;Baumgartner et al 2008;Bendezu and Fontboté 2009;Franchini et al 2015), and has been described previously in the porphyry Cu-Au deposit from Peru (Baumgartner et al 2008;Bendezu and Fontboté 2009;Catchpole et al 2012;Fontboté et al, 2017). However, to our knowledge occurrences of As-goldfieldite and colusite in Canchaque mine (Carlson and Sawkins 1980) and As-goldfieldite in Huanzala mine (Imai et al 1985;Imai 1999) in Peru have never been described before. From a genetic perspective, the distribution, composition, and crystal chemistry of the sulfosalt inclusions help unravel the ore formation in Peruvian deposits.…”

Mineralogy, Fluid Inclusions, and Sulfur Isotopes of the Huanzala Deposits, Peru: Early Skarn and Late Polymetallic Replacement Style Mineralizations

“…Previous papers have reported the ores from the Huanzala deposits to be composed of (i) pyrite with Zn and Pb minerals including sporadic skarn minerals and (ii) Cu minerals accompanied by Ag, Sn, W, and miscellaneous minerals (Imai et al, ; Imai, ). In the present study, six plausible endmember styles of the ores (Fig.…”

“…a). These sulfide orebodies are accompanied by the alteration mineral assemblages of paragonitic sericite, carbonates, quartz, and fluorite (Fukahori et al, ; Saito et al, ; Imai et al, ; Hama et al, ; Imai, ; Murakami et al, ). The late‐stage Zn–Pb orebodies of these assemblages are called “shiroji,” a local Japanese mining term meaning “white‐based” because of their white to light gray color (Hama et al, ; Fukahori & Sakogaichi, ).…”

“…The deposits are linked genetically to the Miocene porphyry intrusions, and the occurrences of massive pyrite, skarn, and replacement‐style orebodies are stratigraphically controlled by steeply dipping (approximately 60°NE) host carbonate rocks of the Lower Cretaceous. Although some technical reports by Japanese geologists have presented detailed descriptions of the geological features of the mining district (Fukahori et al, ; Imai et al, ; Imai, ), its mineralogical and geochemical features have been poorly described.…”

Combined neutralization–adsorption system for the disposal of hydrothermally altered excavated rock producing acidic leachate with hazardous elements

“…The veins occur mainly in altered andesite, which are grouped into Mitsuyama, Koganezawa and Bannozawa (Imai, 1999). The mine produced gold (Au), silver (Ag) and copper (Cu) from 1893 until 1971 (Imai, 1978;Sugimoto, 1952;Watanabe, 1936;Watanabe 1943;Watanabe 1944).…”