Vermiculite is a mineral formed by iron or magnesium silicates, of the mica group. It originates mainly from the hydrothermal alteration of biotite. It is used as an additive in hydroponics and traditional growing media. In hydroponic cultivation, vermiculite floats on water and thus provides the plants with a point of grip and mineral nutrition. In the preparation of substrate mixtures, vermiculite is a very beneficial material, as it has a high capacity to retain water and absorb excess moisture, which can then be released as the substrate dries out. It helps to keep the substrate aerated and its mineral content provides the plants with some of the necessary components for their healthy development.