Wool is the most commonly used material in weaving handmade Persian rugs, mainly because it is soft and durable but also due to the availability of the natural resource to the people of Iran. Although camel or goats hair is sometimes used, in excess it is undesirable. While they may add sheen to a carpet they are very difficult to dye and the rug may loose its color faster than if woven with sheep wool. The best wool generally comes from colder high altitudes and the mountainous topography in parts of Iran is well suited to producing excellent quality. Other wool is imported from Australia and New Zealand who also produce excellent materials. Kork or Kurk wool is regarded the best type of wool, this is high quality wool which is extremely soft yet durable. The wool is shaven from only the shoulders and under-belly of a lamb on its virgin cut. This is when the wool is at its finest and is often used in conjunction with silk.