Silk is a luxury resource. It adds commerce and happiness to the city that works it.
Silk has been a valuable commodity for textiles since its properties were discovered in the 27th century BC. Silk is obtained from the cocoon of the silkworm moth, which was originally native to the forests of China. The fine fibers of the cocoon are woven into cloth, which is used to make all types of clothing. Raw silk was obtained only from Asia until 550 AD, when two monks sent from the Roman Empire secretly stole silkworm eggs from China and brought them to Europe. Eventually, silkworms were found in many areas throughout the world. Less expensive synthetic fibers of the 20th century led to a decline in the silk market, but silk is still very popular in many types of clothing and other goods.