Inclusions: Natural Gypsum crystals generally consist of inclusions, which are foreign minerals or components trapped throughout the crystal composition during development. Frequent inclusions in gypsum might be clay minerals, iron oxides that induce coloration, and even very small gas bubbles. Calcination: The rock is heated in kilns at precise temperatures https://www.propanraya.com/id/produk/eco-gypsum-ee-4050