70 km NW of Ho Chi Minh city.
Placer deposits of
sapphire, transparent yellowish-brown
zircon rest on the slopes and near the bases of volcanic cones.
The placer deposits are closely related to Quaternary (Holocene) trachybasalts, which contain nodules of olivinites. They rest on tholeiitic Neogene-Pleistocene basalt.
Ref: E.Ya. Kievlenko (2003) Geology of gems, p. 67
Gemstone List