Gypsum Are available in hydrothermal veins, which can be fractures in rocks filled with mineral-prosperous fluids that originate from deep within the Earth's crust. Hair or fibre and lime or clay could be added to plasters throughout manufacture. The plaster coats, aside from some end coats, are sanded. See also https://www.propanraya.com/id/produk/eco-gypsum-ee-4050