Prospecting for zircon
placer deposits. Individual grains of blue sapphire, as well as zircon, peridot
were deposited inboard of the intermountain depression in the floodplain and terrace alluvium in the upper reaches of water channels from red clastic deposits of the Neogene molasse.
Ref: E.Ya. Kievlenko, Geology of gems, 2003, p. 63