TrekGEO > Mineral Trail > Kanto region > Gunma pref. > Cosalite

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Hagidaira Mine

Konaka, Azuma village, Midori city, Gunma pref., Japan


Field of view: 5 mm. Cosalite associated with rhodonite. The columnar groups of lead-gray needles are cosalite. The transparent red grains are rhodonite. The cosalite and rhodonite are covered with fine pink rhodochrosite crystals.

Recovered from an open space of a chert-hosted bedded manganese deposit subjected to Hornblende-hornfels facies contact metamorphism by S-type (Ilmenite-series) granodiorite. Formed in the Late Cretaceous (90 Ma).

The first cosalite from Japan was reported from this location in 1960.

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