The Anakie sapphire-bearing region is in the west-flowing streams of the Great Dividing Range, approx 320 km west of Rockhampton. The sapphire-bearing pebble-gravel deposits are distributed over an area exceeding 900 sq. km. They are of Neogene age and lie on Pre-Devonian crystalline schists and granites of the Retreat Complex, Devonian sandstones and schists of the Drummond Group, and undivided Upper Permian deposits. They are covered by Quaternary deposits.
Accumulations with sapphire
grains with zircon
, dark ferruginous spinel
occur in the gravel layers in all operated placer deposits. The sapphire-bearing gravel may have formed from the rewashing of ancient alluvium, which was an intermediate collector of gems. The bottom part of lenses and layers of gravel migrated into trench-like thalwegs of valleys and are most enriched in sapphire
. Most placer deposits are buried to a depth of 10 to 18 m from the surface and are covered by Quaternary sands and clays.
Ref: E.Ya. Kievlenko (2003) Geology of gems, p. 68 - 69
Gem list contains entries from all listed localities in region.
Localities in this Region