Rutile exsolution lamellae of garnet in quartz eclogite from the Sanbagawa Belt, Mt. Gongen, central Shikoku, Japan

Needle-shaped rutile inclusions occur in garnet within the quartz-eclogite at Mt. Gongen Sanbagawa belt, central Shikoku. They are approximately 5–25 µm along long axis and typically oriented three directions, each intersecting 120°. This indicates that needle-shaped is a lamella exsolved from garnet. Garnet with needle-rutile restricted to quartz-poor domain of quartz eclogite sample, which consist quartz, garnet, omphacite, phengite, epidote, kyanite, hornblende. grains lamellae show composition almandine-pyrope series 14–21 mol% grossular content. Rutile exsolution were concentrated range 27–34 pyrope crystals. The host has higher TiO2 content (TiO2 = 0.06–0.19 wt%) than those rutile-free areas. These chemical compositional characteristics suggest Ti was incorporated into crystal structure during growth subsequently partially as retrograde stage. have generally been regarded indicators ultrahigh-pressure metamorphism, but present report where no coesite found, provides evidence natural sample appearance not necessarily under conditions.