Building materials are essential components of any structure. ADOBE is a type of sun-dried brick made from clay and straw, STEEL is an alloy of iron and carbon, SOD is grass and soil held together by its roots, TIMBER is wood cut into beams and planks, STONE is a natural material quarried from the earth, CONCRETE is a mixture of CEMENT, sand, and gravel, GLASS is a transparent material made from sand, CEMENT is a powdery substance made from limestone, SANDSTONE is a sedimentary rock composed of sand and minerals, TILE is a thin, flat piece of material used for covering surfaces, MORTAR is a paste made from sand, water, and CEMENT, STONES are small pieces of rock, STUCCO is a PLASTER-like material used for coating walls, and PLASTER is a material made from lime or gypsum used for coating walls.