Mineral sands are a group of minerals such as ilmenite, rutile and zircon, commonly found together as coarse and fine grain sands. Originally formed as crystals in igneous rocks such as granite or basalt and some metamorphic rocks, these minerals were eroded by wind, rain and rivers over millions of years. The resulting grains washed down to the sea to become part of the coastal sands of ancient beaches. Tidal movements washed away the lighter mineral sand grains, such as quartz sands, leaving the heavier mineral sands on beachlines.
As the world’s oceans subsided, these deposits were left exposed. This natural weathering process formed the two main types of HMS deposits that exist today:
- coarser sands that remained on shorelines due to their larger size, which are often referred to as “strandline” deposits (Strandline); and
- finer mineral sands which typically settled in the basin of the ocean are referred to as “Wimmera Industrial Minerals style” or “offshore” deposits (WIM). WIM style deposits are generally larger overall than Strandline deposits.
The Murray Basin demonstrates this weathering process, where large deposits of HMS formed when heavy minerals entered the marine environment of the Murray Basin through river systems.
Monazite typically contains 50-60% real earth elements by weight and is consistently enriched in the most critical rare earth elements that are essential for high strength permanent magnets.
Source: MCA Mineral Sands May 2020.