R7: Petrology, Mineralogy and Economic geology (Joint Session with Society of Resource Geology)

[R7P-02] Occurrence and formation mechanism of libethenite from Arakawa mine,Akita prefecture, Japan

*Teruhiro Suzuki¹, Yuho Fujimaki¹, Takuya Echigo¹, Yasushi Watanabe¹ (1. Akita Uni. IRS.)

Keywords:Libethenite, Apatite, Arakawa ore depsit, Secondary mineral, Supergene

The Arakawa vein-type Cu deposit has long been known to yeild libethenite. We found libethenite-bearing ores from an outcrop of the Ugaisawa-okuhi vein and report the occurrence of libethenite.
The occurrence of libethenite can be classified into two types: those replacing massive apatite, and those that fill in cracks and voids of the ores. No co-precipitation with limonite was observed in any of the libethenite. These occurrences indicate that libethenite of the Arakawa deposit formed by a supergene reaction of acid, copper-rich meteoric water and primary in the veins.