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Asa river

Hachioji city, Tokyo, Japan



Copal associated with Metasequoia (Metasequoia cfr. gliptostoroboides Hu et Cheng) in tuffaceous sandstone of late Pliocene Kasumi Formation. Kasumi Formation is generally composed of fluvial conglomerate but that of this location is composed of sands and silt in flood plain environment.

Asa river

Outcrop of copal-bearing tuffaceous sandstone of Kasumi Formation. Copal, or young amber, is pine tree resin fossil. The yellow part at the left of the coin is copal. There are white pumice grains in the host, tuffaceous sandstone. Sedimentary sequences are clear at this outcrop from bottom to top: Conglomerate bed composed of pebbles less than 5mm in diameter, sandstone bed, mudstone bed, and tuffaceous sandstone bed. A series of the sequence is approximately 1 meter thick. It seems that copal behaves like pumice in the sedimentary process.

Reported Minerals

Mineral Assemblages

  • Copal - Metasequoia
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