Container of vermiculite, ie that has been artificially expanded mica using heat.
Used mixed with soil, it provides extra oxygen andretains moisture if used in a ratio of 1/5. In addition, it can be used as an inert substrate for hydroponic cultivation cannabis .
Its usefulness comes from its ability to retain water in the fibres, allowing good aeration. It is very light, but as opposed to the other inert substrates like granular perlite it doesn't have the rapid drainage. It also acts as a thermal insulator.
It is recommended to wet it when handling.