Abstract: A fine-grain crystalline mineral selected from the group consisting of vermiculite and hydro-mica is contacted with water to swell the fine grain mineral and the swollen mineral is thereafter comminuted under conditions preserving its crystalline structure to provide a reversibly swellable tri-laminar mineral which is crystalline over a large area and in which the crystal layers or laminations are separated from one another.

Abstract: A process for the gas and liquid-permeable encrusting, pilling and granulating of seed material with the utilization of a three-layer mineral as a laminar coating material which is expandable under the effect of a liquid; the three-layer mineral being constituted of vermiculite or hydrous mica to form the basic material and providing a fine-grained reversibly expandable coating material when applied onto the seed, and which rapidly absorbs and gives off polar liquids such as water. The basic material consists of particles in the form of extremely thin, uniformly even platelets which comprise over 50% of the basic material.