Variations in the environment can cause significant damage -- sub-fossil bone will deteriorate rapidly when exposed to humidity below 45%. Oxidation of pyrites in air is more consistent with electrochemical than bacterial causation and fossils, containing predominantly framboidal and microcrystalline pyrite, can deteriorate if stored at humidity over 65%. Small pyrite samples can be stored in silicone fluid but rigid control of RH is needed for larger specimens. Deterioration of calcareous specimens through growth of calcite may be caused by storage in oak cases. Methods of monitoring the environment are discussed, and some conservation methods used on palaeontological material are presented.