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Crushed and unprocessed Diatomaceous Earth


Purasil is raw Diatomaceous Earth mined from sedimentary layers deposited millions of years ago in a fresh water lake. It is light in weight, chalk-like in appearance, very porous and comprises siliceous fossils of plant algae. It consists primarily of amorphous silica as distinct from crystalline silica or quartz. Amorphous silica is much more soluble than crystalline silica and is not a health hazard.


  • It is used as a soil conditioner to provide plant available silica and improve cation exchange capacity. It is advised that a calcium source (hydrated lime, agricultural lime and or gypsum nitrate) be added at the same time so that the calcium and cations can occupy the sites left by aluminium which is bound by the soluble silica.
  • Coarser grades are available as a growing medium for hydroponics and in orchards.
  • It is used in its raw form on golf courses, sports fields and landscape projects. Landscape gardeners, green keepers and landscape architects use Purasil to improve porosity and drainage of soil and promote the health of the soil's root system.
  • The addition of Purasil to soil helps to promote the healthy growth of living plants. The intricate pore structure of diatoms keeps the pores in the soil open and controls the water supply to the roots, holding and releasing moisture when required. The improved structure oxygenates the soil and helps break up heavy clay.


  • The plant available silica content in the range of 300-350ppm is determined from calcium chloride extraction techniques.
  • Water Absorption – a minimum 100% of its own weight.
  • Melting Point – approximately 1500 ºC
  • Colour – White to light grey
  • Acidity/Alkalinity (pH) - 7.6. This rises to 8.75 upon calcining to 500 ºC. For those applications requiring a pH of 8.75 we recommend the use of Kleensorb.
  • Density – 250 to 450 kg/cubic metre depending on particle size.
  • Cation Exchange Capacity — The measured capacity is 32cmol+/kg which is higher than most soils.
  • Particle Distribution – The rock has been lightly crushed and fragments range from very fine to approximately 5mm.


Silica, like calcium, strengthens cell walls resulting in robust and efficient plants. Silica improves brix levels and therefore flavour. Plants produce more flowers and pollen is more viable resulting in better fruit set. The CSIRO in
Townsville has demonstrated that big increases in yield can be achieved from sugar cane by adding plant available silica to the soil.

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