Vermiculite is light and porous. The material contains few closed pores, which makes it highly aerated. Vermiculite quickly absorbs water and will improve water uptake and distribution. The pH-neutral nature of vermiculite has a certain buffer-capacity of trace elements which occur naturally within the mineral – mainly presented as magnesium and potassium. These elements will partly be released upon the first application of fertilizer.
Vermiculite is a rock with laminar structure, containing mineral water between its layers. At high temperatures this water vaporizes, causing the material to expand. The layers are pressed apart, resulting in a harmonica structure.