“...On Hokkaido, the northernmost large Japanese island is a now unfortunately extinct site for some fairly large agates of different formations. The material was mined over the years in small pits of Hanaishi in the South of the island. The agates were proceeded to jewellery and ornamental objects...
Only a few cut halves were in Collections. The former mining areas are reclaimed for the most part, so no diggings are possible anymore. Onlyone gemstone-cutter in the village still has some raw material....
Agates from Hanaishi are very diverse: up to a size of 20 cm the nodules are containing mostly white, bluish, yellowish band agate. So-called "isolated centres" and eye- and tube-pattern are often observed. Specimen with intense moss- and plumeagatestructures are particularly interesting. These species have been named ”flower-stone” in professional circles. Many of the agates were dyed - in the absence of intense natural colours - prior to further processing or heat treated, a practice which today continues the still flourishing Japanese agate-processing industry with raw material from Uruguay and Brazil...”
written by Johann Zenz in his Book “Agates” (Bode Publishing House 2005) according to personal communication with Hideharu Yamada.
Hideharu Yamada is offering a lot of information about japanese agate and others on his website www.lithos-graphics.com.