Archaeological explanation is given of the pre-historic use and work of jadeite as ornamental stones in Japan, especially around the Niigata Prefecture. How original rocks of jadeite which had been entirely obscured for many centuries were re-discovered in 1939 is explained. Geological and mineralogical occurrences, mineralogical properties of these jadeites, both newly found and archaeologic remains, are described in some details. Jadeites occur as jadeite rock, jadeite-albitite and jadeite vein, in serpentinite masses which develop along the fault boundaries between the green schists and Mesozoic and/or Paleozoic formations. Typical zonal arrangement is, from inner to outer, albite, white jadeite rock, green jadeite rock, soda-rich calciferous amphibole, and host serpentine. The colour of jadeite is white, green, violet and rarely blue and black. The chemical compositions, optical properties, unit cell sizes of jadeites are given.
