Inclusions: Natural Gypsum crystals normally include inclusions, that are international minerals or materials trapped in the crystal framework in the course of formation. Popular inclusions in gypsum could be clay minerals, iron oxides that lead to coloration, or even little gas bubbles. Calcination: The rock is heated in kilns at https://www.propanraya.com/id/produk/eco-gypsum-ee-4050