Regional Report: Kamaishi mine, Kamaishi City, Iwate Prefecture, Tohoku Region, Honshu Island, Japan

An abandoned iron-copper mine at least 500 meters deep. Contact metasomatic (skarn) ores around a Cretaceous dioritic granite intrusion. Worked for iron (magnetite orebodies) and copper-gold-silver (chalcopyrite-cubanite orebodies). At least 15 orebodies, including Shinyama, Nippo, Sahinai and Rasa-Omine orebodies. Shinyama is the largest Fe skarn orebody in Japan, 400m long, 80m wide, 550m high. Magnetite-garnet skarns were worked for iron already during the Tokugawa shogunate era, with Japan's first modern blast furnace built here in 1857 (late Edo era). Peak production was in the 1970s. 1958 production: 1.04 million tons ore averaging 28.6% Fe (the highest Fe ore production in Japan). Mine now closed, but there is commercial production of bottled mineral water. Since the 1990s, the underground mine workings in the northern portion of this mine have been used for estimating long-term stability of geological, hydrogeological, and physicochemical conditions in the rock massif and for studying the migration of natural radionuclides in fractured rocks.

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Bornite - 1, 2

Calcite - 1, 2, 3

Chalcopyrite - 1, 2, 3

'Chlorite Group' - 1

'Clinoptilolite' - 1

'Clinopyroxene Subgroup' - 1, 2

Cobaltite - 2

Copiapite - 1

Copper - 2

Costibite - 1

Cubanite - 1, 2

Cummingtonite - 3

Danburite - 1

Diopside - 1

'Electrum' - 2

Epidote - 1, 3

'Garnet Group' - 2, 3

Gersdorffite - 2

Goethite - 1

Gold - 1, 2

'Grandite' - 1

Grossular - 1

Grunerite - 1, 3

Hedenbergite - 1

'Hornblende' - 1, 2, 3

'K Feldspar' - 2

Kamaishilite - 1

'Küstelite' - 2

Laumontite - 1

Lepidocrocite - 1, 3

Löllingite - 1, 2

Magnetite - 1, 3

Meionite - 1

'Monazite' - 1

Natrolite - 1

Palygorskite - 1

Paracostibite - 1

Pentlandite - 2

Perovskite - 1

Prehnite - 1

Pyrite - 2, 3

Pyrrhotite - 1, 2, 3

Quartz - 1, 2, 3

Safflorite - 1, 2

Schorl - 1

'Sericite' - 1

Silver - 1, 2

Smythite - 1

Sphalerite - 1

Starkeyite - 1

'Stilbite' - 1

Stilpnomelane - 1

Tilleyite - 1

Tochilinite - 1

Uraninite - 1

Vesuvianite - 1

Vonsenite - 1

Wollastonite - 1

Zircon - 1

71 minerals listed.

Locality Key

1	Kamaishi mine, Kamaishi City, Iwate Prefecture, Tohoku Region, Honshu Island, Japan
2	Nippo deposit (Rasa Omine mine), Kamaishi mine, Kamaishi City, Iwate Prefecture, Tohoku Region, Honshu Island, Japan

3	Shinyama deposit, Kamaishi mine, Kamaishi City, Iwate Prefecture, Tohoku Region, Honshu Island, Japan

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