Horticultural Vermiculite

Vermiculite is a mined mineral from the phyllosilicate group resembling Mica. Heat is applied to it that expands it to the accordion shaped pellets composed of multiple layers of thin plates.
It is mainly used to increase moisture and nutrient retention in the grow medium while also providing some aeration.
It will not rot, mould or deteriorate and is non-toxic, sterile and odourless.