The Kornilov Log alluvial-proluvial placer deposit on the bank of the Shilovka River. Pale rubies
and bluish apphires
were found in the lower part of the deluvial deposits on weathered plagiogneiss. The corundum-bearing layer is distinguished by abundant grus and chips of primary rocks and poorly rounded fragments of quartz. Corundum
content is highly irregular and low.
Ref: E. Ya. Kievlenko, Geology of gems, 2003, p. 62