Joshin Mine
Hoshimata, Tsumagoi city, Agatsuma county, Gunma pref., Japan
Occurrence
Neutral metasomatic rocks of Halloysite zone
Halloysite-10Å deposit formed by hydrothermal alteration of andesitic tuff of Middle Pleistocene (0.49 Ma) Nittazawa Lavas erupted from Urakurayama volcanic edifice, Azumaya volcano. It is considered that halloysite was formed by acidic alteration of anorthite in andesite. Ages of volcanic rocks were determined by K-Ar radiometric dating.
Furnace heritages used to produce fire clay by dehydrating halloysite ore.
Reported Minerals
Mineral Assemblages
- Andesite(Host) - Halloysite-10Å
Details of the mine
Joshin mine was first developed to mine aluminum during world war II. After the war, halloysite was mined for material of firebrick.
History
- 1940: Ore was found by Ishizo Hoshikawa during building a charcoal kiln.
- 1941: World War II was started.
- 1943: Aluminum mining was planned by the military authorities.
- 1945: The end of the war.
- 1957: The first furnace was built.
- 1963: The mine was closed because of a fire.
Localities
- Joshin Mine (Halloysite deposit)
Related Occurrences
- Halloysite zone (Alunite zone, Argillized zone)
- Kaolinite zone (Alunite zone, Argillized zone)
- Minamiite-Alunite zone (Alunite zone)
- Pyrophyllite zone
- Smectite zone (Argillized zone)
- Interstratified mineral zone (Argillized zone)
- Illite-Chlorite zone (Propylite zone)
- Epidote-Actinolite zone
- Stilbite-Mordenite zone (Zeolite zone)
- Heulandite-Analcime zone (Zeolite zone)
- Laumontite-Albite zone (Zeolite z., Propylite z.)
- Wairakite-Albite zone (Zeolite zone)