What are Mineral Sands?
Most sand on the beach consists of grains of the mineral quartz (SiO2). Mineral sands are old beach, river or dune sands that contain concentrations of the important minerals rutile, ilmenite, zircon and monazite. These ‘heavy’ minerals have a relative density of between 4 and 5.5g/cm3 and are much heavier than common sand minerals such as quartz which has a density of around 2.65g/cm3. Garnet, magnetite, sapphire, diamond and staurolite are also mined from some mineral sand deposits.
How are Mineral Sands formed?
Rutile, ilmenite, zircon, garnet, magnetite, diamond and monazite are all hard minerals that are resistant to weathering. They all originally grew as crystals in igneous rocks such as granite or basalt and some metamorphic rocks. Over millions of years, these rocks were weathered and eroded. The harder minerals including quartz were washed down to the sea by heavy rainfall and fast flowing streams.
The minerals were then carried back up onto the beach by waves. As the waves washed up and down on the beach, they carried the lighter quartz grains with them back into the sea, leaving the grains of the heavy minerals behind on the beach. Wind also helped to concentrate the heavy minerals by blowing away the lighter quartz sand. These processes were repeated many times over millions of years, eventually creating a large deposit of mineral sands on the beach.
As the sea level rose and fell over geological time, the shoreline also moved. As this happened, the deposits of mineral sand were covered by more sand and built up, or were eroded and redeposited elsewhere. This is why we sometimes find mineral sand deposits many kilometres inland and maybe as much as 50 metres below the surface.
Source: Geoscience, Australia. https://www.ga.gov.au/education/classroom-resources/minerals-energy/australian-mineral-facts/mineral-sands
MRC’s Tormin Mineral Sands Operation consists of four concentrate product streams:
- High Grade Garnet Concentrate
- High Grade Zircon/Rutile Concentrate
- High Grade Ilmenite Concentrate
- Medium Grade Ilmenite Concentrate
Garnet is usually thought of as a gemstone but most garnet is mined for industrial uses. The major industrial uses of garnet are for waterjet cutting purposes, abrasive blasting media, water filtration granules and abrasive powders.
Zircon Rutile Concentrate
Zircon is used in the manufacture of ceramic products including tiles, sanitaryware and tableware and as an opacifier in surface glazes and pigments. Zircon is also the main component in the production of zirconium chemicals used in antiperspirants, paper coatings, paint driers and catalysts. Other main uses for zircon include foundry sand, Cathode Ray Tube television glass and refractories.
Rutile is a form of titanium dioxide mineral.
Titanium dioxide minerals rutile, leucoxene and ilmenite are the principal feedstocks for titanium pigment production. Titanium pigments are used for the manufacture of paints, coatings and plastics and also in other applications such as pharmaceutical, cosmetics, inks and fibres. Titanium dioxide is used in specialist applications including welding rods and also in the production of titanium metal for industrial and aerospace applications.
Ilmenite is the main source of mineral feedstock for titanium dioxide which is used in paints, paper, toothpaste, sunscreen and even food colouring.