Diatomite is a soft, siliceous, chalky, mostly white, sedimentary rock that contains mainly the remains of diatom microfossils.

Diatomite is porous and can hold a lot of water.

However, the main interest in “Diatomite” is its very high Silica content (SiO2 = about 90%). It is the only useful, high in Silica component that can be added to a potting mix. Like Calcium, Silica is an essential component for the growth of orchids and strengthening of cell walls.

What does Diatomite do?

It conditions the soil by making silica available to plants.

It binds aluminum, manganese and heavy metals thus reducing their toxicity.

It improves the availability of calcium and phosphorous.

It helps break up heavy clay.

It helps the soil to retain moisture.

Diatomite contains about 2% crystalline silica (quartz), up to 10% kaolin and up to 5% Montmorillonite. Diatomite also contains small but useful amounts of Phosphorus, Iron, Manganese, Magnesium, Cupper, Calcium, Zinc, Sodium, Potassium and Sulphur.