Prospective alluvial sapphire deposits related to Cenozoic trachybasalt volcanic formations. Modern alluvial placer deposits, in which yellow, green, blue sapphires occur with olivine, pyroxene (enstatite, etc.), black spinel, zircon and pyrope.
Ref: E.Ya. Kievlenko (2003) Geology of gems, p. 68
Gemstone List
Gem list contains entries from all listed localities in region.