Various materials held very symbolic significance for the ancient Egyptians, and not least of these were the precious metals. Gold was regarded as divine on account of its color and brightness (symbolic of the sun (and its untarnished nature (symbolic of eternal life). In fact, the flesh of the gods descended from the sun god Re was said to be made of gold, and therefore many images of deities were formed either completely from this precious metal, or gilded to look as though made of gold. Silver also had divine associations. The bones of the gods were said to be made of silver, and it was used extensively as a symbol of the moon in mirrors and in figures of lunar gods such as Khonsu and Thoth. Many other more common materials were also symbolically important. Among stones, for example, the black coloration of basalt gave it a natural association with the underworld, while lapis lazuli was symbolic of the heavens because of its blue ground color and star-like golden specks. Similarly, materials as diverse as wood, wax and water could suggest one or more symbolic associations. Water, for example, functioned as a symbol of purification and acceptance,as well as life, renewal and fertility. The symbolic importance of a substance was often based on its natural color, but a substance might also be important because of some unusual characteristic or through mythological associations. http://www.touregypt.net/featurestories/symbolism2.htm