Unmanned rock
Unmanned rocks (mumbo-kun, boninite, boninite) are produced in Chichijima of the Ogasawara Islands and have chemical composition of SiO 2\u003e 52%, MgO\u003e 8% and TiO 2\u003e 0.5% A special volcanic rock. It contains no plagioclase and the stone group is vitreous. In 2007, unmanned rocks in Chichijima were selected as one hundred geological features in Japan ("Chichijima Nobody Rock (Boninite)"). ...