This chapter discusses the background and uses, physical and chemical properties, environmental fate and bioaccumulation, mammalian toxicology, industrial hygiene and risk assessment of naturally occurring mineral fibers. Certain mineral fibers include asbestos, erionite and other zeolites, and mineral talc. Asbestos minerals have been known for their useful properties for millennia, and were widely used in the early twentieth century because of characteristics such as superb performance as a flame retardant, low thermal conductivity, tensile strength, and resistance to thermal, electrical, and chemical damage. Asbestos fibers can be released into the air when asbestos containing materials are mined, manufactured, used, or demolished. Fibrous zeolites are not expected to bioaccumulate. Natural fibrous zeolites can be released to the environment from mining or in refined form. True mineral fibers can be present in other forms of talc, either due to asbestos contamination or due to the presence of asbestiform fibers of talc.