“...In the North of the city of Krasnoyarsk in Siberia, Russia basalts occur in the geological environment. Those basalts are sometimes the hostrock for agate-nodules. Agate finds are possible especially in the gravel of the river Kacha, a tributary of the Enisey River. The agates are usually relatively small, but show interesting structures...”

according to personal communication with Prof. Jens Götze, Freiberg