Itoigawa is a city located in Niigata Prefecture, Japan. As of 31 January 2020, the city had an estimated population of 41,333, and a population density of 55 persons per km2. The total area of the city is 746.24 square kilometres (288.12 sq mi).

Jadeite is a pyroxene mineral with composition NaAlSi2O6. It is hard (Mohs hardness of about 6.5 to 7.0), very tough, and dense, with a specific gravity of about 3.4. It is found in a wide range of colors, but is most often found in shades of green or white. Jadeite is formed only in the subduction zones of continental margins, where rock undergoes metamorphism at high pressure but relatively low temperature.