Notes on petrography and rock-forming mineralogy. 3. Albite porphyroblasts containing retrograde TiO2-minerals from Sanbagawa pelitic schists in central Shikoku, Japan.

Abstract

Modes of occurrence of albite porphyroblasts and their inclusion minerals in the Sanbagawa pelitic schists of the Shiragayama area, central Shikoku are described. Albite porphyroblasts in the pelitic schists commonly contain retrograde TiO₂-minerals as well as quartz, garnet, epidote, phengite, biotite, hornblende, ilmenite, rutile, sphene, pyrite, pyrrhotite, chalcopyrite and carbonaceous matters. Textures and chemistries of the retrograde TiO₂-minerals included in the albite porphyroblasts are the same as those of retrograde TiO₂-minerals in the matrix. Albite porphyroblasts included the retograde TiO₂-minerals in retrograde stage of metamorphism.