Ishigaki Island, the second largest of the Okinawa islands, is a mountainous island fringed by coral reefs. Hirakubozaki lighthouse is at the northernmost point of the island. Beach sand from this area is a mixture of biogenic, volcanic and granitic grains.
Geographic Overview
The topography of Ishigaki Island consists of volcanic mountains and limestone terraces that have been altered by successive tectonic forces. The oldest rock that forms the core or foundation of Ishigaki Island consists of schists of metamorphosed sediments and volcanic material subsequently covered by conglomerate, sandstone and limestone.
Sand Gallery
Beach sand from the Hirakubozaki area is rich in well-rounded biogenic grains representing skeletal remains of foraminifera species and fragments of coral, coralline algae, various shells and presence of occasional small gastropod shells, sclerites as well as volcanic grains. Sclerites are elongated translucent structures that are hardened internal spicules of certain sponges and corals.
