Pumice stone 2/4 mm (1 kg 1.5 litres). Pumice is the result of the expansion of an outflowing igneous mineral, creating a honeycomb product of remarkable lightness with high porosity, great water retention and slow release of liquid. As a natural product, it is absolutely ecological and therefore recommended and suitable for horticulture where it is already widely used. Pumice and lapilli are the product of explosive volcanic eruptions created as a result of a violent expansion of gases dissolved in lavas with acidic chemical composition: the rapid cooling of the rock prevented its crystallization, held the gases inside and generated minerals that expanded in more or less pronounced alveoli In fact, the vapours present in the magma that were suddenly released during the solidification phase caused a swelling of the entire magma mass, and during this rapid cooling phase the differences in the physical structure of the different volcanic aggregates were noted. The lower viscosity and slower cooling of the lava facilitated the escape of a certain amount of the gases present in the magma. Chemical physiological properties density: 700? 760 kg/m3 (moist quarry material), 350? 430 kg/m3 (dry material); liquid absorption: approx. 100 g water/100 g pumice stone; CSC: approx. 18 meq/100 g; active limestone: free; pH value: 7 - 8; non-toxic product: (free from crystal clear silica). Media chemical analysis SiO 2: 62.5%; Al2O3: 17.5%; 2O: 9.5%; Fe2O3: 2.6%; CaO: 2.5%; Na2O: 2.2%; TiO 2: 0.5%; MgO: 0.4 . Functional features and areas of application: lighter and more natural