Large amounts of uranium available in the Estonian black alum (Dictyonema) shale created intense interest towards this low-grade ore in the very beginning of the atomic era. Various selective leaching and concentration technologies were tried with both roasted and native shale, at first at the Narva Pilot Plant and thereafter at the Sillamae factory. Even though most of the USSR leading R&D centers participated in this effort, industrial uranium production turned out to be both technologically possible, but at the same time economically untenable at this time, just as it was the case in Sweden.