Anorthite
Oshima Quarry
Shimowada, Nanaho village, Otsuki city, Yamanashi pref., Japan
Field of view: 30 mm. Phenocryst of anorthite. The white crystals are anorthite. The dark red grains are iddingsite formed by alteration of fayalite, and mainly composed of nontronite.
Recovered from basalt erupted from a submarine volcano. Formed in the early Miocene (16 Ma).
Anorthite from this location was described in 1913.
Other localities
- Oshima Quarry (Basalt, Phenocryst)
- Oshima (Pillow lava, Phenocryst)
- Hachijo Island (Basalt lava, Floater)
- Lake Kuttara (Andesite, Floater)