Preservation of Sanukite, the Highly Sophisticated Music Instrument Made of Andesite

Abstract

Sanukite is a special volcanic rock that had erupted about 13 Ma in northern Shikoku of southwest Japan. Petrologically it belongs to aphyric andsite. Sanukite is much harder and finer-grained than the ordinary volcanic rocks. Although its density is 2.60 g/cm³, its P-wave velocity is about 6 km/s. This high P-wave velocity is unique characteristics of sanukite. Dr. Hitoshi Maeda made the first stone xylophone (“sekkin” petrophone) in 1981. He has continued the analyses into the specific vibrational properties and wave forms of sanukite and he created many musical instruments of stone known by the name “Sanukitephone.” We believe that sanukite and Sanukitephones will be the future World Heritage. Sanukite is globally important rock and its resource is limited. As sanukite is the symbolic rock of Sanuki District (Kagawa Prefecture), we must hurry to establish preservation system as one of the member of the Global Geopark Network.