The strongest tissue of the body made up of organic and inorganic materials is called bone. The volatile matrix consists of 40% organic matter and 60% inorganic mineral salts. Contains collagen and asimucoid (mucopolysaccharide) as organic matter. Inorganic materials include calcium carbonate, calcium phosphate, calcium chloride and magnesium phosphate. Bones are hard because they contain calcium salts in the matrix. It contains 97% calcium. The ossified membrane is called periosteum. The periosteum is attached to the bone by Sharpey’s fibers. The lining of the unstable medullary cavity is called the endosteum.