Vermiculite: "Family" name for a number of complex hydrated Magnesium – Aluminium – Silicates, formed as an alteration product of biotite or phlogopite by weathering or hydrothermal action.  Empirical formula: Mg1.8Fe2+0.9Al4.3SiO10(OH)2•4(H2O)

It is a natural mineral that expands with the application of heat the same way as Perlite expands. It is lightweight, compressible, absorbent and non reactive. It is not surprising that both Perlite and Vermiculite are used in horticulture for the same reasons: Both provide aeration and drainage, retain water, are sterile and free from diseases. Both have a fairly neutral pH, non-toxic and relatively inexpensive.

We have two products sharing the same name: "Vermiculite" the natural occurring mineral, and "Vermiculite" the compound, result of the natural occurring Vermiculite superheated.

After the heat treatment, natural Vermiculite expands into light pebbles that hold more water than Perlite. The chemical composition of Vermiculite differs widely from Perlite: Vermiculite is a hydrated Magnesium – Aluminium – Silicate, but Perlite is a hydrated Aluminium – Silicate with very little Magnesium.  Vermiculite contains small amounts of Fe, Ca, K and Ti, much less than Perlite.

Perlite is a superior product to use as it lasts longer (decomposes much slower) and has a more neutral pH.