【mineral photo】classic rhodochrosite specimen from Tohoku area, Japan

From many hydrothermal deposits in Tohoku area (Northern part of the Honshu Island), many good specimens of rhodochrosite had been found. Especially from Oppu Mine and Osarizawa Mine, beautiful banded mammillary rhodochrosite specimens had been produced.

Link to Mindat
・Oppu Mine => https://www.mindat.org/loc-6437.html
・Osarizawa Mine => https://www.mindat.org/loc-17459.html

↓These are very large specimens in the museum. Two specimens behind are from Oppu Mine, and the others are from Osarizawa Mine.

This rhodochrosite from Osarizawa Mine is one of my collection. Photo width is about 5 cm. Interior of the mammillary rhodochrosite conotain some small euhedral crystals.

↓This is the favorite specimen in my collection! This specimen is also from Osarizawa Mine, and photo width is about 10 cm. Rhodochrosite covers hydrothermal quartz-sulfide ore. Under the rhodochrosite ore, there were possibly euhedral crystals of chalcopyrite. The chalcopyrite would be desolved by the hydrothermal fluid.

Because inside of the rhodochrosite cover is vacunt, it is not pseudomorph crystal but shell structure. Triangle vacunts suggest a single crystal of chalcopyrite, and six-star shaped cross section does twin crystal of chalcopyrite.

Link to planetscope page of rhodochrosite(菱マンガン鉱)