Drywall is a modern building material that comes in large panels (typically 4' by 8') having a gypsum core sandwiched between two heavy paper faces. These paper faces are often made from recycled paper. One face is smooth and is the surfacing face, and the other is more of a kraft paper backing face.
This is the common name for the mineral "halite". Its chemical formula is NaCl. ... It can have impurities of gypsum (CaSO4) and sylvite (KCl) but it is very rare to find potassium sulfate as a mineral, although occasionally polyhalite (K2Ca2Mg(SO4)) is found associated with rock salt deposits. 2.