History and geology
Erosion of the Australian Alps between the last five to ten million years has formed many mineral sands deposits. The eroded minerals were carried down rivers to the sea. Here they settled and formed deposits. Often further concentration was caused by wind and wave action. The most famous mineral sands province formed from the Australian Alps is the Murray Basin, which has billions of tonnes of mineral sands.
Australia is rich in mineral sands and is the world’s largest producer. Close examination of the sand on most Australian beaches will reveal a small amount of black sand amongst the quartz. This is usually mineral sands, albeit in an uneconomic concentration.
The Gippsland Basin deposits formed from rivers flowing south out of the Alps into the Southern Ocean.
The Glenaladale deposit was discovered in 2004 by Rio Tinto and is the first significant mineral sands discovery made in Gippsland. Rio Tinto carried out extensive drilling, metallurgical and feasibility studies until it was acquired by Kalbar in 2013.
Kalbar’s initial drilling indicated the Glenaladale deposit was most prospective for an economic project.
The Glenaladale deposit is a sequence of around 30 mineralised layers extending over around 15km from Stockdale to Glenaladale. In the Northern areas the deposit is close to surface, and dips at about 1 degree to the South. The layers appear to have formed due to pooling at offshore bars, which enabled enrichment of some layers due to wave action.
Over the course of six drilling campaigns and associated metallurgical studies, Kalbar discovered and defined a discrete orebody within the Glenaladale deposit called the Marker Horizon, located in the Fingerboards area. This orebody is one of the highest grade in the world.
The deposit can be broadly divided into the Lower Layers and Upper Layers. The Lower Layers are lower grade and have a lower value assemblage. The Upper Layers have higher grade and better assemblage.
The Marker Horizon is part of the Upper Layers and it is the Marker Horizon that makes the Fingerboards Mineral Sands Project economic. The zircon grade of the project area is also high, with zircon being the most valuable of the heavy minerals.
Kalbar’s exploration activity has increased the Glenaladale resource from 1.7Bt to 2.7Bt of heavy mineral. It is one of the biggest mineral sands deposits in the world and the Fingerboards zone has one of the highest grades