Jadeite from the Horokanai-Kamietanbetsu area in the Kamuikotan zone, Hokkaido.

Jadeitic pyroxenes are found from the metabasites of a coherent suite of high-pressure rocks in the Horokanai-Kamietanbetsu area. Jadeitic pyroxene-bearing rocks occur as massive bundins or schistose rocks intercalated with Na-amphibole-albite-bearing basic schists. Jadeitic pyroxenes are associated with Na-amphibole, lawsonite, chlorite, aragonite, albite and quartz. XJa of jadeitic pyroxenes in contact with quartz and albite ranges from 0.56 to 0.74. The mode of occurrence and XJa of jadeitic pyroxenes suggest that the Kamuikotan high-pressure sequence in the study area was formed in the albite stability field and close to that of jadeite-quartz assemblage.