Izumi Kogane-zuka Kofun, located at Uedai-chô, Izumi City, Osaka Prefecture, is a large keyhole-shaped tomb mound built at the tip of Shinodayama Hill. The mound measures 94 m long, its round back is 60 m in diameter and the rectangular front is 42 m in width. Surrounded by shield-shaped ditches, the overall length of the whole site is 115 m. On the side of the mound are Fukiishi (paving stones covering the outside of burial mounds), with Entô-Haniwa (cylindrical clay figures) surrounding the site. Iegata-Haniwa (house-shaped clay figures) and Kizai-Haniwa (tool-shaped clay figures) were also excavated around the narrow part of the mound.
During excavation and research conducted in 1950 - 1951, three Nendo-kaku (a chamber made of clay to house coffins) were discovered in the rear round part: Chuo-kaku (center chamber), Higashi-kaku (east chamber) and Nishi-kaku (west chamber). In the Chuo-kaku were the Waritake-gata Mokkan (giant hollowed wooden coffins) and in the Higashi-kaku and Nishi-kaku were the Hako-gata Mokkan (box-shaped wooden coffins). Many relics were discovered inside and around the coffins of the three chambers. Shaen-Nishin-Nijûkyô (a triangular-rimmed frame mirror with two pairs of deity and beast pictures), comma-shaped jewels, gemstones (amber, jadeite, glass or crystal), tubular shaped beads, ring-shaped stone bracelets and wheel-shaped stone bracelets were discovered in the coffin in the center chamber. Gamontai-Dôkôshiki-Shinjûkyô (a wide imaged frame mirror with deity-and-beast pictures facing one way) with the inscription "third year of Keisho era," single-edged iron swords, iron swords, iron axes and iron sickles were discovered around the coffin. From the Higashi-kaku, Sankakuen-Banryûkyô (a triangular-rimmed frame mirror with dragon pictures), 2 plates of Gamontai-Kanjônyu-Shinjûkyô (a wide imaged frame mirror with deity-and-beast pictures), armor, comma-shaped jewels, gemstones (amber, jadeite, glass, or crystal), tubular shaped beads, beads, large crystal faceted gems and Kuwagata-ishi (hoe-shaped stone objects with an elliptical hole in the center) were discovered in the coffin and iron lances, iron pikes and iron arrowheads were discovered around the coffin. From the Nishi-kaku, Gamontai-Dôkôshiki-Shinjûkyô, comma-shaped jewels, gemstones (amber, jadeite, glass, or crystal), tubular shaped beads, single-edged iron swords, iron swords, iron arrowheads and copper arrowheads were discovered. Of all this large amount of unearthed articles, the Gamontai-Dôkôshiki-Shinjûkyô, which was found around the coffin in the center chamber, has an inscription of "the third year of Jinchu (Keisho) era (239)" of the Wei Dynasty, China, which can be considered to be related to the one hundred bronze mirrors sent from Wei to Himiko, the queen of the Yamatai Kingdom as a gift as described in the "Gishiwajinden" (Records of Wei: Biography of the Wa people).
The unearthed articles of Izumi Kogane-zuka Kofun are valued as an exemplary set of burial accessories and ornaments of the early Kofun era within the district and it holds an important place in the research of the Kofun era.