Neither. Technically, wool is only produced by domesticated sheep.
Qiviut is the undercoat of the Arctic muskox, a relative of sheep and goats (not cattle, despite being called an ‘ox’). It is shed naturally in spring. Only about half of the shed or less is suitable for spinning into yarn. The fibre itself is very fine (around 18 microns), warmer and stronger than wool, non-itchy, and – like hair – does not felt.
The vicuña is a wild South American camelid, related to the alpaca and llama. Vicuña do not do well in captivity, so they are rounded up and sheared every 2–3 years. The amount of fibre is tiny – only 500g or so. Unlike qiviut, vicuña doesn’t take dye well, so it’s only available in its natural golden-brown shade. Like alpaca, the fibre is hollow, and its fine scales allow it to interlock to retain warmth. Each fibre is 8–13 microns thick, making it one of the finest known – only angora hair, from angora rabbits, is of a similar fineness.
The main difference is that muskoxen can be farmed, but vicuña can’t. As a result, qiviut is cheaper. Both, however, are high-end luxury fibres.
Originally appeared on Quora.