Three main factors determine the quality of preserved material in a coal ball: the mineral constituents, the speed of the burial process, and the degree of compression before undergoing permineralisation.[39] Generally, coal balls resulting from remains that have a quick burial with little decay and pressure are better preserved, although plant remains in most coal balls almost always show differing signs of decay and collapse.[10] Coal balls containing quantities of iron sulfide have far lower preservation than coal balls permineralised by magnesium or calcium carbonate,[10][40][41] which has earned iron sulfide the title "chief curse of the coal ball hunter".[31]