Animal fibers are natural fibers that consist largely of particular proteins. The animal fibers used most commonly both in the manufacturing world as well as by the hand spinners are Wool from domestic sheep and silk. Also very popular are alpaca and camel fiber.
Not all animal fibers have the same properties, and even within a species (Cashmere ↔ Mohair or Alpaca ↔ Camel) the fiber is not consistent. With animal fibers, and natural fibers in general, the individual fibers look different, whereas all synthetic fibers look nearly the same. This provides an easy way to differentiate between natural and synthetic fibers under a microscope. As an example Silk with it specific shape is the blue print for many todays synthetic filament fibres, but it’s extraordinary properties classify it as an ultimate natural fibre.
Download: The Animal Fibres Factsheet