Rock Crystal Museum, a fireproof reinforced concrete building, was constructed in 1927 in the same place as it is found today. The faculty of liberal arts of Yamanashi University started to take care of the building in 1949, before it became a government-owned property in 1956. It is currently managed by our Earth Science group of Science Education Course. The Museum has a display of rough rock crystals and crystal jewelries and ornaments that were donated by Kokichi Momose. Momose, who was in drug and pharmaceutical business, was a jewel and mineral ore appraiser in the late 19th and early 20th centuries. Some rock crystal brought in for appraisal spurred him to collect crystals at his own expense. His thirty-odd years since the late 1890s were devoted to collection and preservation of crystals, leaving him with an excellent accumulation. Our exhibits mainly consist of crystals from Yamanashi Prefecture and neighboring regions, winning a worldwide reputation. Yamanashi surpasses any other prefecture in the number of crystal mines and the amount of crystal produced, and the quality of its crystal is outstanding both in form and clarity. Especially our large achromatic single crystal and Japanese twin crystal, the kind first discovered in Japan and in the world, given the name "Japanese Twin" or "Japanese Law Twin," stand unrivaled. Our display of crystal ornaments traces the history of crystal polishing technology and crystal work since the end of Tokugawa era, or the mid 19th century. (The Museum tours are possible if requested in advance. Please visit the Japanese Web site of the Museum for further details. Click here.)